{"id":3702,"date":"2016-10-23T00:00:40","date_gmt":"2016-10-23T04:00:40","guid":{"rendered":"https:\/\/underhost.com\/blog\/?p=3702"},"modified":"2026-10-23T09:49:24","modified_gmt":"2026-10-23T13:49:24","slug":"patch-protect-vulnerability-dirty-cow","status":"publish","type":"post","link":"https:\/\/underhost.com\/blog\/patch-protect-vulnerability-dirty-cow\/","title":{"rendered":"Dirty COW and Other Linux Kernel Flaws: How to Check and Patch Your Kernel (2026)"},"content":{"rendered":"<div class=\"uh-blog-hero\" style=\"margin:0 0 40px;text-align:center;padding:48px 24px;border-radius:20px;background:linear-gradient(135deg,#0D1F3C 0%,#125A8A 58%,#176EA5 100%);color:#ffffff;box-shadow:0 20px 40px -15px rgba(13,31,60,0.28);position:relative;overflow:hidden;\">\n<div style=\"display:inline-flex;align-items:center;gap:8px;padding:7px 14px;margin-bottom:16px;border:1px solid rgba(0,212,255,0.32);border-radius:999px;color:#DFF8FF;font-size:12px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;background:rgba(0,212,255,0.10);\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Linux<\/div>\n<h1 style=\"color:#ffffff;font-size:clamp(32px,5vw,46px);line-height:1.12;margin:0 0 14px;font-weight:800;\">Dirty COW and Other Linux Kernel Flaws: How to Check and Patch Your Kernel (2026)<\/h1>\n<\/div>\n<div class=\"uh-blog-excerpt\" style=\"border-left:4px solid #00D4FF;padding:18px 20px;margin:0 0 34px;background:#F8FAFC;color:#1F2937;border-radius:0 14px 14px 0;box-shadow:0 8px 28px rgba(13,31,60,0.08);line-height:1.75;\"><strong style=\"color:#0D1F3C;\">Short answer:<\/strong> Dirty COW is a 2016 Linux kernel flaw that let a local user gain root. Every supported Linux release has been patched for years, so if your server gets regular updates, you are safe from it. What matters today is the same habit for newer kernel flaws: update the kernel package, reboot or live-patch so the new kernel actually runs, and check the running version with <code>uname -r<\/code>.<\/div>\n<nav aria-label=\"Table of contents\" class=\"uh-toc\" style=\"background:#ffffff;border:1px solid #E5E7EB;border-radius:16px;padding:20px 22px;margin:0 0 34px;box-shadow:0 4px 12px rgba(13,31,60,0.08);\">\n<div style=\"font-size:12px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;color:#176EA5;margin-bottom:10px;\"><i class=\"fas fa-list\" style=\"color:#00D4FF;\"><\/i> In this guide<\/div>\n<ol style=\"margin:0;padding-left:20px;columns:2 260px;column-gap:28px;line-height:1.9;\">\n<li><a href=\"#what-dirty-cow-was\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">What Dirty COW was<\/a><\/li>\n<li><a href=\"#is-my-server-still-affected\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Is my server still affected?<\/a><\/li>\n<li><a href=\"#newer-kernel-flaws-that-work-the-same-way\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Newer kernel flaws that work the same way<\/a><\/li>\n<li><a href=\"#how-attackers-use-kernel-flaws\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">How attackers use kernel flaws<\/a><\/li>\n<li><a href=\"#containers-vps-and-the-kernel\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Containers, VPS and the kernel<\/a><\/li>\n<li><a href=\"#step-1-check-your-running-kernel\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 1: check your running kernel<\/a><\/li>\n<li><a href=\"#step-2-update-the-kernel\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 2: update the kernel<\/a><\/li>\n<li><a href=\"#step-3-make-the-new-kernel-run\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 3: make the new kernel run<\/a><\/li>\n<li><a href=\"#step-4-confirm-the-fix\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Step 4: confirm the fix<\/a><\/li>\n<li><a href=\"#turn-on-automatic-security-updates\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Turn on automatic security updates<\/a><\/li>\n<li><a href=\"#reduce-the-risk-from-the-next-kernel-flaw\" style=\"color:#176EA5;text-decoration:none;font-weight:600;\">Reduce the risk from the next kernel flaw<\/a><\/li>\n<\/ol>\n<\/nav>\n<div class=\"uh-post-content\" style=\"color:#1F2937;font-size:16px;line-height:1.75;\">\n<h2 id=\"what-dirty-cow-was\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-info-circle\" style=\"color:#00D4FF;\"><\/i> What Dirty COW was<\/h2>\n<p style=\"margin:0 0 18px;\">Dirty COW, tracked as <strong>CVE-2016-5195<\/strong>, was a race condition in the way the Linux kernel handled copy-on-write memory. A local user, or a compromised website process, could use it to write to files that should have been read-only, and from there gain root access. The flaw had been in the kernel for about nine years before it was found and fixed in October 2016.<\/p>\n<p style=\"margin:0 0 18px;\">The name comes from &#8220;copy-on-write&#8221;, shortened to COW. It became one of the best-known Linux flaws because public exploits were easy to use and worked on most servers of the time.<\/p>\n<h2 id=\"is-my-server-still-affected\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-server\" style=\"color:#00D4FF;\"><\/i> Is my server still affected?<\/h2>\n<p style=\"margin:0 0 18px;\">Almost certainly not, if the server runs a supported release and gets updates. Any kernel from a supported distribution released after late 2016 includes the fix. You are only at risk on a very old system that has not been updated since, such as CentOS 6 or an early CentOS 7 kernel. Those systems have other, newer flaws too, and should be replaced.<\/p>\n<h2 id=\"newer-kernel-flaws-that-work-the-same-way\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-angle-double-right\" style=\"color:#00D4FF;\"><\/i> Newer kernel flaws that work the same way<\/h2>\n<div style=\"overflow-x:auto;margin:26px 0;border:1px solid #E5E7EB;border-radius:14px;-webkit-overflow-scrolling:touch;\">\n<table style=\"width:100%;border-collapse:collapse;background:#ffffff;color:#1F2937;font-size:15px;line-height:1.55;margin:0;min-width:600px;\">\n<thead>\n<tr style=\"background:#0D1F3C;color:#fff;\">\n<th style=\"padding:14px;text-align:left;\">Flaw<\/th>\n<th style=\"padding:14px;text-align:left;\">Year<\/th>\n<th style=\"padding:14px;text-align:left;\">What it allowed<\/th>\n<th style=\"padding:14px;text-align:left;\">Fixed in<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Dirty COW, CVE-2016-5195<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">2016<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Local user to root through copy-on-write memory<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Kernel updates from October 2016<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Dirty Pipe, CVE-2022-0847<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">2022<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Overwriting read-only files through pipes, leading to root<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Kernels 5.16.11, 5.15.25 and 5.10.102, and distribution updates<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Copy Fail, CVE-2026-31431<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">2026<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Local privilege escalation through the kernel crypto code<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">2026 kernel updates. See our <a href=\"https:\/\/underhost.com\/blog\/cve-2026-31431-copy-fail-linux-server-patch-guide\/\">Copy Fail guide<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">GhostLock and JanusCape, CVE-2026-43499 and CVE-2026-53359<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">2026<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">Local privilege escalation and virtual machine escape<\/td>\n<td style=\"padding:14px;border-top:1px solid #E5E7EB;vertical-align:top;\">2026 kernel updates. See our <a href=\"https:\/\/underhost.com\/blog\/ghostlock-and-januscape-what-self-managed-linux-server-owners-need-to-patch-now\/\">GhostLock and JanusCape guide<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p style=\"margin:0 0 18px;\">These flaws all need local access first, for example through a hacked website, a stolen SSH login, or another customer on a shared server. That is why they matter most on shared hosting servers and on servers that run code you do not fully trust.<\/p>\n<h2 id=\"how-attackers-use-kernel-flaws\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-shield-alt\" style=\"color:#00D4FF;\"><\/i> How attackers use kernel flaws<\/h2>\n<p style=\"margin:0 0 18px;\">A kernel flaw is usually the second step of an attack, not the first. A typical chain looks like this:<\/p>\n<ol style=\"margin:0 0 24px;padding-left:22px;\">\n<li style=\"margin:0 0 8px;\">The attacker breaks into a website, for example through an outdated plugin, and gets a shell as the website user.<\/li>\n<li style=\"margin:0 0 8px;\">They run an exploit for a kernel flaw to turn that limited account into root.<\/li>\n<li style=\"margin:0 0 8px;\">With root, they can hide files, add users, read every site on the server, or install malware.<\/li>\n<\/ol>\n<p style=\"margin:0 0 18px;\">Signs that this may have happened include new user accounts, unknown cron jobs, changed system files, and processes you do not recognise. Tools such as <a href=\"https:\/\/underhost.com\/blog\/how-to-install-rkhunter-on-linux-rootkit-hunter\/\">rkhunter<\/a> and <a href=\"https:\/\/underhost.com\/blog\/how-to-install-linux-malware-detect\/\">Linux Malware Detect<\/a> help you check. If you find signs of a root compromise, the safest fix is a clean rebuild from known-good backups.<\/p>\n<h2 id=\"containers-vps-and-the-kernel\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-server\" style=\"color:#00D4FF;\"><\/i> Containers, VPS and the kernel<\/h2>\n<ul style=\"margin:0 0 24px;padding-left:22px;\">\n<li style=\"margin:0 0 8px;\"><strong>KVM virtual servers<\/strong> run their own kernel. Patch the kernel inside your VPS, just as you would on a physical server.<\/li>\n<li style=\"margin:0 0 8px;\"><strong>Containers<\/strong> such as Docker share the host&#8217;s kernel. Updating the container image does not fix a kernel flaw: the host kernel must be patched.<\/li>\n<li style=\"margin:0 0 8px;\"><strong>Virtualisation hosts<\/strong> need extra care. A flaw like JanusCape affects the host kernel, so the provider must patch the host.<\/li>\n<\/ul>\n<h2 id=\"step-1-check-your-running-kernel\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 1: check your running kernel<\/h2>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code># The kernel that is running now\nuname -r\n\n# Your distribution and release\ncat \/etc\/os-release<\/code><\/pre>\n<p style=\"margin:0 0 18px;\">Compare the version with your distribution&#8217;s security notice for the flaw you are checking.<\/p>\n<h2 id=\"step-2-update-the-kernel\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 2: update the kernel<\/h2>\n<h3 style=\"color:#0D1F3C;font-size:21px;line-height:1.3;margin:26px 0 10px;\">AlmaLinux, Rocky Linux, RHEL and CloudLinux<\/h3>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code>sudo dnf upgrade kernel\n\n# Has a newer kernel been installed than the one running?\nsudo dnf install -y dnf-utils\nsudo needs-restarting -r<\/code><\/pre>\n<h3 style=\"color:#0D1F3C;font-size:21px;line-height:1.3;margin:26px 0 10px;\">Debian and Ubuntu<\/h3>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code>sudo apt update &amp;&amp; sudo apt upgrade\n\n# Ubuntu and Debian create this file when a reboot is needed\nls \/var\/run\/reboot-required &amp;&amp; cat \/var\/run\/reboot-required<\/code><\/pre>\n<h2 id=\"step-3-make-the-new-kernel-run\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 3: make the new kernel run<\/h2>\n<p style=\"margin:0 0 18px;\">Installing a kernel update does not protect you until the server runs the new kernel. You have two options:<\/p>\n<ul style=\"margin:0 0 24px;padding-left:22px;\">\n<li style=\"margin:0 0 8px;\"><strong>Reboot.<\/strong> The simplest and most reliable option. Plan a short maintenance window, then check <code>uname -r<\/code> again.<\/li>\n<li style=\"margin:0 0 8px;\"><strong>Live patching.<\/strong> Services such as KernelCare, Canonical Livepatch on Ubuntu, or kpatch on RHEL-based systems apply security fixes to the running kernel without a reboot. They are useful for servers that cannot go down often. You still reboot onto a full kernel update from time to time.<\/li>\n<\/ul>\n<h2 id=\"step-4-confirm-the-fix\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-terminal\" style=\"color:#00D4FF;\"><\/i> Step 4: confirm the fix<\/h2>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code>uname -r                     # should show the new kernel version\nsudo needs-restarting -r     # RHEL family: should say no reboot is needed<\/code><\/pre>\n<p style=\"margin:0 0 18px;\">On Ubuntu and Debian, the <code>\/var\/run\/reboot-required<\/code> file should be gone after the reboot.<\/p>\n<h2 id=\"turn-on-automatic-security-updates\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-shield-alt\" style=\"color:#00D4FF;\"><\/i> Turn on automatic security updates<\/h2>\n<p style=\"margin:0 0 18px;\">Automatic updates install fixes as soon as your distribution releases them. You still need to reboot for kernel updates.<\/p>\n<pre style=\"background:#0D1F3C;color:#EAF6FF;padding:18px 20px;border-radius:14px;overflow-x:auto;line-height:1.7;font-size:15px;\"><code># AlmaLinux, Rocky Linux, RHEL, CloudLinux\nsudo dnf install -y dnf-automatic\n# In \/etc\/dnf\/automatic.conf set: apply_updates = yes\nsudo systemctl enable --now dnf-automatic.timer\n\n# Debian and Ubuntu\nsudo apt install -y unattended-upgrades\nsudo dpkg-reconfigure -plow unattended-upgrades<\/code><\/pre>\n<p style=\"margin:0 0 18px;\">On cPanel servers, keep cPanel updates on as well, in <strong>WHM &gt; Update Preferences<\/strong>.<\/p>\n<h2 id=\"reduce-the-risk-from-the-next-kernel-flaw\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-exclamation-triangle\" style=\"color:#00D4FF;\"><\/i> Reduce the risk from the next kernel flaw<\/h2>\n<ul style=\"list-style:none;padding-left:0;\">\n<li style=\"margin:0 0 8px;\">\u2713 Install updates automatically, or at least weekly, and reboot after kernel updates.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 Keep websites and plugins updated, because a hacked site is the usual way attackers get local access.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 Disable SSH password logins and use keys, so stolen passwords are less useful.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 On shared servers, use account isolation such as CloudLinux CageFS.<\/li>\n<li style=\"margin:0 0 8px;\">\u2713 Subscribe to your distribution&#8217;s security announcements.<\/li>\n<\/ul>\n<p style=\"margin:0 0 18px;\">For hands-on hardening, see our <a href=\"https:\/\/underhost.com\/blog\/how-to-install-and-configure-csf-firewall-on-your-server\/\">CSF firewall guide<\/a> and our <a href=\"https:\/\/underhost.com\/blog\/top-cpanel-security-tips-to-keep-your-hosting-environment-safe\/\">cPanel security tips<\/a>.<\/p>\n<div aria-hidden=\"true\" class=\"uh-section-divider\" style=\"width:min(100% - 32px, 1080px);margin:44px auto;display:grid;grid-template-columns:1fr 32px 1fr;align-items:center;gap:18px;pointer-events:none;\"><span style=\"height:1px;background:linear-gradient(90deg,transparent,rgba(0,212,255,0.40),rgba(23,110,165,0.24),transparent);\"><\/span><img alt=\"\" decoding=\"async\" height=\"32\" loading=\"lazy\" src=\"https:\/\/cdn.underhost.com\/android-chrome-192x192.webp\" style=\"width:32px;height:32px;display:block;border-radius:8px;filter:drop-shadow(0 0 14px rgba(0,212,255,0.30));\" width=\"32\"\/><span style=\"height:1px;background:linear-gradient(90deg,transparent,rgba(23,110,165,0.24),rgba(0,212,255,0.40),transparent);\"><\/span><\/div>\n<\/div>\n<div class=\"uh-blog-cta\" style=\"background:linear-gradient(135deg,#0D1F3C 0%,#125A8A 58%,#176EA5 100%);color:#ffffff;padding:36px 24px;border-radius:20px;text-align:center;margin:44px 0;box-shadow:0 20px 40px -15px rgba(13,31,60,0.32);\">\n<h2 style=\"margin:0 0 12px;font-size:28px;line-height:1.25;color:#ffffff;\">Need help with this?<\/h2>\n<p style=\"font-size:17px;margin:0 auto 22px;color:#EAF6FF;max-width:720px;line-height:1.7;\">Do not want to track kernel flaws yourself? Our server management team patches and reboots your server for you.<\/p>\n<p><a href=\"https:\/\/underhost.com\/server-management.php\" style=\"background:linear-gradient(90deg,#00D4FF,#0077FF);color:#ffffff;padding:13px 28px;border-radius:10px;text-decoration:none;font-weight:800;display:inline-block;margin:8px;\">See server management plans<\/a><a href=\"https:\/\/customerpanel.ca\/client\/\" style=\"background:transparent;color:#ffffff;padding:12px 28px;border-radius:10px;text-decoration:none;font-weight:800;display:inline-block;margin:8px;border:1px solid rgba(255,255,255,0.32);\">Contact @CustomerPanel<\/a><\/div>\n<div class=\"uh-faq-section\" id=\"faq\" style=\"margin:34px 0;scroll-margin-top:90px;\">\n<h2 style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:0 0 18px;border-bottom:2px solid rgba(0,212,255,0.22);padding-bottom:10px;\">Frequently asked questions<\/h2>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">Is Dirty COW still a threat in 2026?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">Not on supported, updated systems. The fix has been in every supported Linux release since late 2016. Only very old, unpatched systems are still affected.<\/p>\n<\/div>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">How do I know if my kernel is patched?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">Run uname -r to see the running kernel and compare it with your distribution&#8217;s security notice. On RHEL-based systems, needs-restarting -r tells you if a newer kernel is installed but not yet running.<\/p>\n<\/div>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">Do I need to reboot after a kernel update?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">Yes, unless you use a live patching service. The fix only works once the server runs the new kernel.<\/p>\n<\/div>\n<div style=\"margin-top:18px;background:#F8FAFC;padding:18px 20px;border-radius:14px;border:1px solid rgba(23,110,165,0.14);\">\n<h3 style=\"color:#0D1F3C;margin:0 0 8px;font-size:19px;\">Are UnderHost managed servers patched for kernel flaws?<\/h3>\n<p style=\"margin:0;color:#1F2937;line-height:1.7;\">Our managed and shared hosting servers are patched by our team. If you run an unmanaged VPS or dedicated server, updating the kernel is your responsibility, or you can add server management.<\/p>\n<\/div>\n<\/div>\n<p><!-- uh-related-start --><\/p>\n<div style=\"background:#F4F8FC;border:1px solid #DCE7F3;border-radius:14px;padding:18px 22px;margin:32px 0 8px;\">\n<h2 style=\"margin:0 0 12px;font-size:22px;\">Related guides<\/h2>\n<ul style=\"margin:0;padding-left:20px;\">\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/how-to-fsck-a-linux-filesystem\/\">How to Check and Repair a Linux Filesystem With fsck<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/nodejs-security-update-october-2026-cve-2026-111497\/\">Node.js Security Update (October 2026): CVE-2026-111497<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/php-security-release-october-2026-patch-guide\/\">PHP Critical Security Update (October 2026): Patch Guide, CloudLinux Status, CERT-EU Advice and Mitigations<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/imunify360-vs-cpguard-which-security-suite-fits-your-hosting-needs\/\">Imunify360 vs cPGuard: Which Security Suite Fits Your Hosting Needs?<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/underhost.com\/blog\/how-to-use-cdn-content-delivery-networks-to-boost-website-speed-and-security\/\">&#x26a1; How to Use CDN (Content Delivery Networks) to Boost Website Speed and Security<\/a><\/li>\n<\/ul>\n<\/div>\n<p><!-- uh-related-end --><br \/>\n<script type=\"application\/ld+json\">{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Is Dirty COW still a threat in 2026?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Not on supported, updated systems. The fix has been in every supported Linux release since late 2016. Only very old, unpatched systems are still affected.\"}}, {\"@type\": \"Question\", \"name\": \"How do I know if my kernel is patched?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Run uname -r to see the running kernel and compare it with your distribution's security notice. On RHEL-based systems, needs-restarting -r tells you if a newer kernel is installed but not yet running.\"}}, {\"@type\": \"Question\", \"name\": \"Do I need to reboot after a kernel update?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes, unless you use a live patching service. The fix only works once the server runs the new kernel.\"}}, {\"@type\": \"Question\", \"name\": \"Are UnderHost managed servers patched for kernel flaws?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Our managed and shared hosting servers are patched by our team. If you run an unmanaged VPS or dedicated server, updating the kernel is your responsibility, or you can add server management.\"}}]}<\/script><\/p>\n<h2 id=\"sources\" style=\"color:#0D1F3C;font-size:28px;line-height:1.25;margin:34px 0 14px;scroll-margin-top:90px;\"><i class=\"fas fa-book\" style=\"color:#00D4FF;\"><\/i> Sources<\/h2>\n<ul style=\"margin:0 0 24px;padding-left:22px;\">\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/access.redhat.com\/security\/cve\/cve-2016-5195\">Red Hat: CVE-2016-5195 (Dirty COW)<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/access.redhat.com\/security\/cve\/cve-2022-0847\">Red Hat: CVE-2022-0847 (Dirty Pipe)<\/a><\/li>\n<li style=\"margin:0 0 8px;\"><a href=\"https:\/\/ubuntu.com\/security\/notices\">Ubuntu security notices<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Dirty COW is a 2016 Linux kernel flaw that let a local user gain root. Every supported Linux release has been patched for years, so if your server gets regular updates, you are safe from it. What matters today is the same habit for newer kernel flaws: update the kernel package, reboot or live-patch so the new kernel actually runs, and check the running version with uname -r.<\/p>\n","protected":false},"author":1,"featured_media":3710,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[25,203],"tags":[113,115,188,186,182,114],"class_list":["post-3702","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-linux","category-security","tag-tag-debian","tag-tag-linux-server","tag-patch","tag-security-updates","tag-server-management","tag-tag-ubuntu"],"_links":{"self":[{"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/posts\/3702","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/comments?post=3702"}],"version-history":[{"count":11,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/posts\/3702\/revisions"}],"predecessor-version":[{"id":7005,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/posts\/3702\/revisions\/7005"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/media\/3710"}],"wp:attachment":[{"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/media?parent=3702"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/categories?post=3702"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/underhost.com\/blog\/wp-json\/wp\/v2\/tags?post=3702"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}