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  4. CVE 2025 21759 ipv6 mcast extend rcu protection in igmp6send
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Back to active CVEs
High · CVSS 7.8CVE-2025-21759

ipv6: mcast: extend RCU protection in igmp6_send()CVE-2025-21759

Answer in brief

CVE-2025-21759 records a High severity (CVSS 7.8) vulnerability in ipv6: mcast: extend RCU protection in igmp6_send(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Feb 27, 2025Updated Oct 3, 2026Source checked Nov 4, 2026First seen by HOL Aug 5, 2026Material review Oct 3, 2026
Upstream Advisory

Record context

Vulnerability class
Memory Corruption
EPSS
Not reported
CWE IDs
CWE-416
Source
CVE List V5
Source checked
Nov 4, 2026
References
7 linked sources
Open source record

Key facts

Risk
High · CVSS 7.8
Exploitation
Not marked as known exploited
Affected software
6 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
ProductAffected versionsFixed versions
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*Not reportedNot reported
Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Linux/Linuxgeneric>=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <81b25a07ebf53f9ef4ca8f3d96a8ddb94561dd5a || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <0bf8e2f3768629d437a32cb824149e6e98254381 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <8e92d6a413feaf968a33f0b439ecf27404407458 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <087c1faa594fa07a66933d750c0b2610aa1a294681b25a07ebf53f9ef4ca8f3d96a8ddb94561dd5a, 0bf8e2f3768629d437a32cb824149e6e98254381, 8e92d6a413feaf968a33f0b439ecf27404407458, 087c1faa594fa07a66933d750c0b2610aa1a2946
Linux/Linuxgeneric2.6.26Not reported
Linux/Linuxgeneric>=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <638e8fe3563a82f298fe537a28d5342a97278cf1 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <6901bbb169e3add6c037218d996790cef6b3d650 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <7e0a818ecc4d62e7fb668ea02de0bfe8ba0b7dff || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <81b25a07ebf53f9ef4ca8f3d96a8ddb94561dd5a || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <0bf8e2f3768629d437a32cb824149e6e98254381 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <8e92d6a413feaf968a33f0b439ecf27404407458 || >=b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 <087c1faa594fa07a66933d750c0b2610aa1a2946638e8fe3563a82f298fe537a28d5342a97278cf1, 6901bbb169e3add6c037218d996790cef6b3d650, 7e0a818ecc4d62e7fb668ea02de0bfe8ba0b7dff, 81b25a07ebf53f9ef4ca8f3d96a8ddb94561dd5a, 0bf8e2f3768629d437a32cb824149e6e98254381, 8e92d6a413feaf968a33f0b439ecf27404407458, 087c1faa594fa07a66933d750c0b2610aa1a2946

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux, Linux/Linux.
  2. 2Review the reported fix. Update Linux/Linux to 81b25a07ebf53f9ef4ca8f3d96a8ddb94561dd5a; Linux/Linux to 638e8fe3563a82f298fe537a28d5342a97278cf1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Feb 27, 2025

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 3, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Aug 5, 2026

Sources and claim methodology

  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
Upstream source description

In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: extend RCU protection in igmp6_send() igmp6_send() can be called without RTNL or RCU being held. Extend RCU protection so that we can safely fetch the net pointer and avoid a potential UAF. Note that we no longer can use sock_alloc_send_skb() because ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep. Instead use alloc_skb() and charge the net->ipv6.igmp_sk socket under RCU protection.

Quoted source text, attributed separately from HOL analysis.