Account Center


  1. Portal Home
  2. Knowledgebase
  3. Linux知識
  4. How To Protect Your Server Against the Dirty COW Linux Vulnerability

How To Protect Your Server Against the Dirty COW Linux Vulnerability

Introduction : On October 19, 2016, a privilege escalation vulnerability in the Linux kernel was disclosed. The bug is nicknamed Dirty COW because the underlying issue was a race condition in the way kernel handles copy-on-write (COW). Dirty COW has existed for a long time at least since 2007, with kernel version 2.6.22 so the vast majority of servers are at risk.

Exploiting this bug means that a regular, unprivileged user on your server can gain write access to any file they can read, and can therefore increase their privileges on the system. More information can be found on CVE-2016-5195 from Canonical, Red Hat, and Debian.

Check Vulnerability :


To find out if your server is affected, check your kernel version.

# uname -rv

You’ll see output like this:
4.4.0-42-generic #62-Ubuntu SMP Fri Oct 7 23:11:45 UTC 2016

If your version is earlier than the following, you are affected:

  • 4.8.0-26.28 for Ubuntu 16.10
  • 4.4.0-45.66 for Ubuntu 16.04 LTS
  • 3.13.0-100.147 for Ubuntu 14.04 LTS
  • 3.2.0-113.155 for Ubuntu 12.04 LTS
  • 3.16.36-1+deb8u2 for Debian 8
  • 3.2.82-1 for Debian 7
  • 4.7.8-1 for Debian unstable

If you’re on CentOS, you can use this script provided by RedHat to test your server’s vulnerability. To do so, first download the script.


Then run it with bash.

# bash

If you’re vulnerable, you’ll see output like this:

Your kernel is 3.10.0-327.36.1.el7.x86_64 which IS vulnerable.
Red Hat recommends that you update your kernel. Alternatively, you can apply partial
mitigation described at .

Fix Vulnerability

Fortunately, applying the fix is straightforward: update your system and reboot your server.


Update and upgrade your packages using apt-get.

# sudo apt-get update && sudo apt-get dist-upgrade

You’ll need to reboot your server to apply the changes.

# sudo reboot


At this time, we’re still waiting for Red Hat to release a patch. This tutorial will be updated with instructions on how to secure your CentOS server as soon as possible. In the interim, you can use this workaroundfrom the Red Hat bug tracker.


Make sure to update your Linux servers to stay protected from this privilege escalation bug.

  • 2 Users Found This Useful
Was this answer helpful?

Related Articles


经我们在测试机测试,Ubuntu 14.04可以成功升级到内核4.9.6,以下是为更换方法,供大家参考:1. 下载新内核wget...

Ubuntu 16.04升级到内核4.9.8

经测试,Ubuntu 16.04可以成功升级到内核4.9.8,以下是为更换方法,供大家参考:1. 下载新内核(示例为64位,请大家根据自己的实际版本到官方下载对应内核)wget...