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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 24 Mar 2022.
Ubuntu LinuxOperating system · Canonical

CVE-2016-5195

HIGH · 7.0 CVSS v3.1 Published 2016-11-10
Fix available
A fix is available. Upgrade to 3.2.83 / 3.4.113 or later.
See remediation →
96/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect handling of a copy-on-write (COW) feature to write to a read-only memory mapping, as exploited in the wild in October 2016, aka "Dirty COW."

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A race condition in mm/gup.c in Linux kernel versions 2.x through 4.x (before 4.8.3) allows local users to bypass copy-on-write (COW) protections, enabling writes to read-only memory mappings and privilege escalation.

MitigationUpgrade the Linux kernel to version 4.8.3 or later, or apply the corresponding backported security patch. For systems where immediate patching is infeasible, consider compensating controls such as restricting local shell access or using SELinux/AppArmor to limit privilege escalation vectors.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 16.04= 16.10
Linux KernelOperating system
Affected:>= 2.6.22, < 3.2.83>= 3.3, < 3.4.113>= 3.5, < 3.10.104>= 3.11, < 3.12.66>= 3.13, < 3.16.38>= 3.17, < 3.18.44>= 3.19, < 4.1.35>= 4.2, < 4.4.26>= 4.5, < 4.7.9>= 4.8, < 4.8.3
Enterprise LinuxOperating system
Affected:= 5= 6.0= 7.0
Enterprise Linux AusOperating system
Affected:= 6.2= 6.4= 6.5
Enterprise Linux EusOperating system
Affected:= 6.6= 6.7= 7.1
Enterprise Linux Long LifeOperating system
Affected:= 5.6= 5.9
Enterprise Linux TusOperating system
Affected:= 6.5
Debian LinuxOperating system
Affected:= 7.0= 8.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the running kernel version
    Run `uname -r` or `cat /proc/version` to obtain the exact kernel version string
    Affected if The kernel version falls within any of the affected ranges: >= 2.6.22 and < 3.2.83; >= 3.3 and < 3.4.113; >= 3.5 and < 3.10.104; >= 3.11 and < 3.12.66; >= 3.13 and < 3.16.38; >= 3.17 and < 3.18.44; >= 3.19 and < 4.1.35; >= 4.2 and < 4.4.26; >= 4.5 and < 4.7.9; >= 4.8 and < 4.8.3
  2. Confirm the distribution and version
    Run `cat /etc/os-release` or check distribution-specific files such as `/etc/lsb-release` for Ubuntu, `/etc/redhat-release` for RHEL, or `/etc/debian_version` for Debian
    Affected if The system runs Ubuntu 12.04, 14.04, 16.04, or 16.10; RHEL 5, 6.0, 6.2, 6.4, 6.5, 6.6, 6.7, 7.0, 7.1, or specific long life/aus/eus/tus variants; or Debian 7.0 or 8.0, and the kernel has not been patched
  3. Check if user namespaces are enabled
    Inspect the kernel config with `cat /boot/config-$(uname -r) | grep CONFIG_USER_NS` or verify runtime status with `sysctl user.max_user_namespaces`
    Affected if User namespaces are enabled (CONFIG_USER_NS=y) as this is a common exploitation vector for Dirty COW privilege escalation, though the vulnerability can be exploited without this
  4. Verify if the vulnerability is patched in the installed kernel
    Check for the presence of the fix commit in the kernel by examining `/proc/version_signature` on Ubuntu or running `rpm -q kernel` to list installed kernel packages and compare against distribution security advisories
    Affected if The installed kernel lacks the CVE-2016-5195 fix and remains within the affected version ranges listed above

A system is affected if it runs a Linux kernel within the vulnerable version ranges (2.x through 4.x before 4.8.3) from the listed distributions without the security patch applied.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.2.83 / 3.4.113 / 3.10.104 or later
Fixed in 3.2.833.4.1133.10.104
Vendor patch git.kernel.org →
Interim mitigation

Upgrade the Linux kernel to version 4.8.3 or later, or apply the corresponding backported security patch. For systems where immediate patching is infeasible, consider compensating controls such as restricting local shell access or using SELinux/AppArmor to limit privilege escalation vectors.

Recommended fix High confidence

Linux kernel 4.8.3 or later; or distribution-specific patched kernels (Ubuntu 16.04.1+ with kernel 4.8.0+, RHEL/CentOS 7 with kernel 3.10.0-514+, Debian 8.8+ with kernel 3.16.43+)

  1. 1. Identify your current kernel version using 'uname -r'
  2. 2. For Ubuntu/Debian: Run 'sudo apt-get update && sudo apt-get dist-upgrade' to install the latest kernel security patches, or manually install linux-image-<version> for version 4.8.3 or later
  3. 3. For RHEL/CentOS/Enterprise Linux: Run 'sudo yum update kernel' to install the patched kernel
  4. 4. For other distributions: Obtain kernel version 4.8.3 or later from your vendor's stable repository
  5. 5. Reboot the system to load the patched kernel: 'sudo reboot'
  6. 6. Verify the fix by running 'uname -r' to confirm the new kernel version and checking that it is 4.8.3 or later, or that your distribution's security advisory confirms the patch is applied
Caveat Kernel upgrades may require system reboot and could potentially cause issues with proprietary kernel modules or drivers that are not compatible with the new version; test in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ubuntu Linux Exploited in the wild — priority engagement
  • Consultation6.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
26.0 hours of engineering $4,560
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-5195 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data