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VulnerabilityPublished Updated

CVE-2025-39977: Linux kernel · futex: Prevent use-after-free during requeue-PI

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 7.8 High · fixed in 6.8.0-1050.53~22.04.1 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.8.0-1050.53~22.04.1, 6.8.0-1051.57~22.04.1, 6.8.0-1052.55~22.04.1 +32
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Oct 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 25.10linuxpkg:deb/ubuntu/linux@6.17.0-6.6?arch=source&distro=questingOther threatsAffected
  • <6.17.0-6.6
Fixed in
  • 6.17.0-6.6
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1003.3?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1006.6?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1006.6
Fixed in
  • 6.17.0-1006.6
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 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1003.3?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1003.3?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3

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

AI-suggested

A patch is available and should be applied to affected Linux kernel versions. The Ubuntu security advisory USN-8095-1 confirms the fix is included in updated linux-hwe-edge kernel packages. Users should update to the fixed kernel versions as provided by their distribution. No additional mitigations are indicated by the vendor advisory.

Description

A use-after-free vulnerability in the Linux kernel futex subsystem related to requeue-PI operations has been resolved. The flaw involves improper synchronization in futex_wait_requeue_pi(), which can lead to use of freed memory during task wakeup. This issue was detected by syzbot and fixed by ensuring futex_q::task is read before updating the requeue state to prevent race conditions. The vulnerability affects multiple specific Linux kernel versions in the linux-hwe-edge product line. A patch is available and has been released by Ubuntu as part of a broader Linux kernel security update addressing multiple issues.

References

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