CVE-2025-21777

Kernel crash via duplicate ring-buffer subbuffer indexes

Published Feb 27, 2025 · Updated May 11, 2026

Improper validation in Linux kernel 6.12, 6.13, and 6.14 release candidates allows attackers to crash the kernel via duplicate metadata indexes. The persistent ring-buffer metadata validator checks each subbuffer index only for range, then builds a linked list without rejecting duplicates. Exploitation requires corrupted persistent metadata with duplicate writer-side indexes; the public record identifies no route for supplying that metadata.

CVSS severityUnavailable
Unscored
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

Improper validation in Linux kernel 6.12, 6.13, and 6.14 release candidates allows attackers to crash the kernel via duplicate metadata indexes. The persistent ring-buffer metadata validator checks each subbuffer index only for range, then builds a linked list without rejecting duplicates. Exploitation requires corrupted persistent metadata with duplicate writer-side indexes; the public record identifies no route for supplying that metadata.

The record

CVE
CVE-2025-21777
Published
Feb 27, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
Unavailable
Privileges
Unavailable

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=c76883f18e59b762247ee91d3e4224231711854e <0d547a6f5e8fad26ebc12f501d7d19fccdbad6bf
  3. Affected versionversion=c76883f18e59b762247ee91d3e4224231711854e <3ec743d558f111d8999aea24577ba66c65ee2eeb
  4. Affected versionversion=c76883f18e59b762247ee91d3e4224231711854e <f5b95f1fa2ef3a03f49eeec658ba97e721412b32

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=6.12; version=c76883f18e59b762247ee91d3e4224231711854e <0d547a6f5e8fad26ebc12f501d7d19fccdbad6bf; version=c76883f18e59b762247ee91d3e4224231711854e <3ec743d558f111d8999aea24577ba66c65ee2eeb; version=c76883f18e59b762247ee91d3e4224231711854e <f5b95f1fa2ef3a03f49eeec658ba97e721412b32

Published CVSS scores

No CVSS assessment is available in this record.

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)
VectorUnavailable
PrivilegesUnavailable
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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