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VulnerabilityPublished Updated

CVE-2025-39989: Linux kernel · x86/mce: use is_copy_from_user() to determine copy-from-user context

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1046.49~22.04.1 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.8.0-1046.49~22.04.1, 6.8.0-1051.57~22.04.1, 6.8.0-1047.50~22.04.2 +30
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Apr 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threatsAffected
  • 6.17.0-1003.3 – 6.17.0-1017.17
10 affected builds
Fixed in–
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux@6.8.0-100.100?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-100.100
Fixed in
  • 6.8.0-100.100
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@6.8.0-1046.49?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1046.49
Fixed in
  • 6.8.0-1046.49
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@6.8.0-1046.52?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1046.52
Fixed in
  • 6.8.0-1046.52
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11@6.11.0-1018.18~24.04.1?arch=source&distro=nobleOther threatsAffected
  • <6.11.0-1018.18~24.04.1
Fixed in
  • 6.11.0-1018.18~24.04.1
Ubuntu 24.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.8.0-1061.68?arch=source&distro=nobleOther threatsAffected
  • 6.8.0-1041.48 – 6.8.0-1061.68
6 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

An official patch is available and should be applied to affected Linux kernel versions. The patch restores correct handling of copy-from-user contexts and fixes race conditions in memory failure handling. Users should update to the fixed kernel versions as provided by their Linux distribution vendors. No additional mitigation is required beyond applying the official fix.

Description

A vulnerability in the Linux kernel's x86 machine check exception (MCE) handling related to memory failure recovery was resolved. The issue caused kernel panics or user process termination due to improper handling of poisoned memory pages during copy-from-user operations and instruction fetching. The problem arose from changes in exception table fixup types that broke recovery logic and a race condition between memory controller interrupts and core machine checks on Intel platforms. The fix restores proper error handling to prevent kernel crashes and allows user processes to recover or be safely terminated. This vulnerability affects certain Linux kernel versions and has been addressed by an official patch.

References

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