CVE-2025-21813

Timer migration disruption via root misconnection

Published Feb 27, 2025 · Updated May 23, 2026

An off-by-one error in Linux kernel 6.12.11 through 6.12.13 and 6.13 allows local users to disrupt timer migration. The timers/migration code tests a pre-accounted new root for one child instead of two, omitting the old-root connection and permitting multiple top levels. Local low-privileged access is required; the inconsistent timer hierarchy can trigger a kernel warning, with no reported confidentiality or integrity impact.

CVSS severity5.5
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An off-by-one error in Linux kernel 6.12.11 through 6.12.13 and 6.13 allows local users to disrupt timer migration. The timers/migration code tests a pre-accounted new root for one child instead of two, omitting the old-root connection and permitting multiple top levels. Local low-privileged access is required; the inconsistent timer hierarchy can trigger a kernel warning, with no reported confidentiality or integrity impact.

The record

CVE
CVE-2025-21813
Published
Feb 27, 2025
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-193
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=12ead225b7996252a8bc1a49b03aad57c0794880 <c6dd70e5b465a2b77c7a7c3d868736d302e29aec
  2. Affected versionversion=6.12.11 <6.12.14
  3. Affected versionversion=6.13
  4. Affected versionversion=b729cc1ec21a5899b7879ccfbe1786664928d597 <6f449d8fa1808a7f9ee644866bbc079285dbefdd
  5. Affected versionversion=b729cc1ec21a5899b7879ccfbe1786664928d597 <868c9037df626b3c245ee26a290a03ae1f9f58d3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=12ead225b7996252a8bc1a49b03aad57c0794880 <c6dd70e5b465a2b77c7a7c3d868736d302e29aec; version=6.12.11 <6.12.14; version=6.13; version=b729cc1ec21a5899b7879ccfbe1786664928d597 <6f449d8fa1808a7f9ee644866bbc079285dbefdd; version=b729cc1ec21a5899b7879ccfbe1786664928d597 <868c9037df626b3c245ee26a290a03ae1f9f58d3

Published CVSS scores

5.5NIST NVDCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-193Off-by-one Error

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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