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VulnerabilityPublished Updated

CVE-2025-21764: Linux kernel · ndisc: use RCU protection in ndisc_alloc_skb()

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 7.8 High.

Data as of 10 Nov 2026, 14:02 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.

Sources agree

CVSS scores by source
CNA (Linux)CVSS 3.17.8
CISA-ADPCVSS 3.17.8
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Feb 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

AI-suggested

The vulnerability has been resolved by adding RCU protection in the ndisc_alloc_skb() function. Although no explicit patch links are provided, the fix is confirmed by the vendor advisory stating the issue is resolved. Users should update their Linux kernel to the fixed version once available.

Description

CVE-2025-21764 is a use-after-free vulnerability in the Linux kernel's ndisc_alloc_skb() function due to missing RCU protection. This flaw allows the function to be called without holding RTNL or RCU locks, potentially leading to memory corruption. The vulnerability has a high severity with a CVSS score of 7.8, impacting confidentiality, integrity, and availability.

References

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