CVE-2025-21902

Kernel warning via unnecessary ACPI UCSI synchronization

Published Apr 1, 2025 · Updated May 23, 2026

Denial of service in Linux kernel 6.12.5 through 6.12.18 and 6.13 allows local users to trigger a kernel warning through ACPI UCSI. The ACPI UCSI backend forces an embedded-controller-to-opregion synchronization while the core is not polling CCI, and some firmware mishandles that unnecessary operation. Reachability requires local access and a system whose BIOS exposes the affected ACPI UCSI implementation; the documented consequence is an assertion warning in ucsi_reset_ppm.

CVSS severity6.8
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux kernel 6.12.5 through 6.12.18 and 6.13 allows local users to trigger a kernel warning through ACPI UCSI. The ACPI UCSI backend forces an embedded-controller-to-opregion synchronization while the core is not polling CCI, and some firmware mishandles that unnecessary operation. Reachability requires local access and a system whose BIOS exposes the affected ACPI UCSI implementation; the documented consequence is an assertion warning in ucsi_reset_ppm.

The record

CVE
CVE-2025-21902
Published
Apr 1, 2025
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 1, 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=6.12.5 <6.12.19
  2. Affected versionversion=6.13
  3. Affected versionversion=c0ca6fd5f6ebde8fc0df8bb5c32629d1284f60d0 <012b98cdb54c7d47743ee7fc402fa23f2d90529a
  4. Affected versionversion=fa48d7e81624efdf398b990a9049e9cd75a5aead <1aec5c9066965ac0984e385bbc31455ae31cbffc
  5. Affected versionversion=fa48d7e81624efdf398b990a9049e9cd75a5aead <976e7e9bdc7719a023a4ecccd2e3daec9ab20a40

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.12.5 <6.12.19; version=6.13; version=c0ca6fd5f6ebde8fc0df8bb5c32629d1284f60d0 <012b98cdb54c7d47743ee7fc402fa23f2d90529a; version=fa48d7e81624efdf398b990a9049e9cd75a5aead <1aec5c9066965ac0984e385bbc31455ae31cbffc; version=fa48d7e81624efdf398b990a9049e9cd75a5aead <976e7e9bdc7719a023a4ecccd2e3daec9ab20a40

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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

No sourced classifications are available.

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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