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VulnerabilityPublished Updated

CVE-2026-80733: Linux kernel · net: remove WARN_ON_ONCE() from sk_mc_loop()

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f625c742b33dc137c209dd13d1c5f12b1c18d71c : update Linux kernel when convenient.

Data as of 6 Nov 2026, 17:40 UTC

Severity
Low

Rated Low by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch
Available – fixed in f625c742b33dc137c209dd13d1c5f12b1c18d71c, d2adc4e80b29e58b5162ae09f0f657a215806c8c, c8f256dc849205ccb2bd78bd99a3497b972b44e0 +8

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Sep 2026

  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 6 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • >=3.14.40 <3.15
  • >=3.18.13 <3.19
  • >=3.19.6 <3.20
Fixed in
  • f625c742b33dc137c209dd13d1c5f12b1c18d71c
  • d2adc4e80b29e58b5162ae09f0f657a215806c8c
  • c8f256dc849205ccb2bd78bd99a3497b972b44e0
  • b8a39a09ae4eaae04309e1e38ed6a1101d967496
  • ad7fa2f411cb30f63d6725f111be134064cdb718
  • ad7dbb1d14b1b4406eca8ef9478e8de312ba0cfe
  • 97133c4d42654578fab95abe47359ebe784dde18
  • 3.20
  • 3.19
  • 3.15
  • 0d75f2c1d0764efa756ad9c1e078d8c09ea8fc1f
LinuxLinuxAffected
  • =4.0
Fixed in–

AI-suggested

This issue has been fixed in Linux kernel versions 3.15, 3.19, and 3.20 and their corresponding commits. Users should upgrade to these or later versions to eliminate the warning. No additional mitigation is required as the fix addresses the root cause.

Description

A Linux kernel vulnerability was fixed by removing a WARN_ON_ONCE() call from the sk_mc_loop() function. The issue occurred when sk_mc_loop() was called on sockets that are neither AF_INET nor AF_INET6, such as AF_PACKET sockets used over virtual devices. In these cases, the function triggered a warning incorrectly because non-INET sockets do not support certain multicast loop options. The fix ensures that loopback defaults to true without generating a warning for these socket types.

References

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