CVE-2025-21771

Local denial of service via misclassified migration

Published Feb 27, 2025 · Updated May 11, 2026

Incorrect migration handling in Linux 6.12 allows local users to trigger a kernel warning during a cgroup task move. scx_move_task() tests only the destination cgroup and PF_EXITING, so it mistakes a racing root-cgroup move for an autogroup move and skips notifying the BPF scheduler. Reachability requires sched_ext cgroup scheduling and a non-root-to-root-autogroup migration; the published impact is limited to availability, with no reported data access or modification.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect migration handling in Linux 6.12 allows local users to trigger a kernel warning during a cgroup task move. scx_move_task() tests only the destination cgroup and PF_EXITING, so it mistakes a racing root-cgroup move for an autogroup move and skips notifying the BPF scheduler. Reachability requires sched_ext cgroup scheduling and a non-root-to-root-autogroup migration; the published impact is limited to availability, with no reported data access or modification.

The record

CVE
CVE-2025-21771
Published
Feb 27, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.12
  2. Affected versionversion=8195136669661fdfe54e9a8923c33b31c92fc1da <75bf2f80c046d2ec5a07455891ea0a9fb6d8b5f6
  3. Affected versionversion=8195136669661fdfe54e9a8923c33b31c92fc1da <d6f3e7d564b2309e1f17e709a70eca78d7ca2bb8
  4. Affected versionversion=8195136669661fdfe54e9a8923c33b31c92fc1da <d8b510d0ddc65d8a71e0f9a3acc9ed5f010fc514

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.12; version=8195136669661fdfe54e9a8923c33b31c92fc1da <75bf2f80c046d2ec5a07455891ea0a9fb6d8b5f6; version=8195136669661fdfe54e9a8923c33b31c92fc1da <d6f3e7d564b2309e1f17e709a70eca78d7ca2bb8; version=8195136669661fdfe54e9a8923c33b31c92fc1da <d8b510d0ddc65d8a71e0f9a3acc9ed5f010fc514

Published CVSS scores

5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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