CVE-2025-21852

Local kernel crash via nullable tracepoint pointer

Published Mar 12, 2025 · Updated May 11, 2026

NULL pointer dereference in the Linux kernel from 6.11 allows local users to crash the system through a crafted BPF tracepoint program. The BPF verifier fails to mark the optional rx_sk argument to trace_kfree_skb as nullable, so it accepts a program that dereferences a null socket pointer. Loading and reaching the tracepoint requires local low-privileged access; successful exploitation raises a kernel page fault and interrupts the host.

CVSS severity5.5
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

NULL pointer dereference in the Linux kernel from 6.11 allows local users to crash the system through a crafted BPF tracepoint program. The BPF verifier fails to mark the optional rx_sk argument to trace_kfree_skb as nullable, so it accepts a program that dereferences a null socket pointer. Loading and reaching the tracepoint requires local low-privileged access; successful exploitation raises a kernel page fault and interrupts the host.

The record

CVE
CVE-2025-21852
Published
Mar 12, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 12, 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=6.11
  2. Affected versionversion=c53795d48ee8f385c6a9e394651e7ee914baaeba <4dba79c1e7aad6620bbb707b6c4459380fd90860
  3. Affected versionversion=c53795d48ee8f385c6a9e394651e7ee914baaeba <5da7e15fb5a12e78de974d8908f348e279922ce9
  4. Affected versionversion=c53795d48ee8f385c6a9e394651e7ee914baaeba <f579afacd0a66971fc8481f30d2d377e230a8342

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.11; version=c53795d48ee8f385c6a9e394651e7ee914baaeba <4dba79c1e7aad6620bbb707b6c4459380fd90860; version=c53795d48ee8f385c6a9e394651e7ee914baaeba <5da7e15fb5a12e78de974d8908f348e279922ce9; version=c53795d48ee8f385c6a9e394651e7ee914baaeba <f579afacd0a66971fc8481f30d2d377e230a8342

Published CVSS scores

5.5CISA ADPCVSS: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 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-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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