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VulnerabilityPublished Updated

CVE-2025-21771: Linux kernel · sched_ext: Fix incorrect autogroup migration detection

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 5.5 Medium.

Data as of 29 Oct 2026, 23:28 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
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 27 Feb 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: 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 29 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSlinux-raspi-realtimepkg:deb/ubuntu/linux-raspi-realtime?arch=source&distro=nobleOther threatsAffected
  • =6.8.0-2019.20
Fixed in–
Ubuntu 22.04 LTSlinux-allwinner-5.19pkg:deb/ubuntu/linux-allwinner-5.19?arch=source&distro=jammyOther threatsAffected
  • 5.19.0-1007.7~22.04.1 – 5.19.0-1015.15~22.04.1
8 affected builds
Fixed in–
Ubuntu 22.04 LTSlinux-aws-5.19pkg:deb/ubuntu/linux-aws-5.19?arch=source&distro=jammyOther threatsAffected
  • 5.19.0-1019.20~22.04.1 – 5.19.0-1029.30~22.04.1
10 affected builds
Fixed in–
Ubuntu 22.04 LTSlinux-aws-6.2pkg:deb/ubuntu/linux-aws-6.2?arch=source&distro=jammyOther threatsAffected
  • 6.2.0-1005.5~22.04.1 – 6.2.0-1018.18~22.04.1
14 affected builds
Fixed in–
Ubuntu 22.04 LTSlinux-aws-6.5pkg:deb/ubuntu/linux-aws-6.5?arch=source&distro=jammyOther threatsAffected
  • 6.5.0-1008.8~22.04.1 – 6.5.0-1024.24~22.04.1
14 affected builds
Fixed in–
Ubuntu 22.04 LTSlinux-azure-5.19pkg:deb/ubuntu/linux-azure-5.19?arch=source&distro=jammyOther threatsAffected
  • 5.19.0-1020.21~22.04.1 – 5.19.0-1027.30~22.04.2
7 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

A fix is available that modifies sched_move_task() to explicitly indicate the migration type and restricts scx_move_task() usage to cgroup migrations only. Users should apply the updated Linux kernel versions that include this patch to resolve the issue.

Description

CVE-2025-21771 addresses a flaw in the Linux kernel's scheduler extension where the function scx_move_task() incorrectly detects autogroup migrations. This caused the function to ignore certain migrations improperly, leading to kernel warnings. The issue was fixed by modifying sched_move_task() to explicitly indicate the type of migration, ensuring scx_move_task() is only called for cgroup migrations.

References

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