CVE-2026-80733: Linux kernel · net: remove WARN_ON_ONCE() from sk_mc_loop()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in f625c742b33dc137c209dd13d1c5f12b1c18d71c : update Linux kernel when convenient.
Data as of 6 Nov 2026, 17:40 UTC
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
Disclosed: evidence found.
CVE published 3 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| 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
- git.kernel.org/stable/c/97133c4d42654578fab95abe47359ebe784dde18 (opens in a new tab)
- git.kernel.org/stable/c/f625c742b33dc137c209dd13d1c5f12b1c18d71c (opens in a new tab)
- git.kernel.org/stable/c/ad7fa2f411cb30f63d6725f111be134064cdb718 (opens in a new tab)
- git.kernel.org/stable/c/d2adc4e80b29e58b5162ae09f0f657a215806c8c (opens in a new tab)
- git.kernel.org/stable/c/ad7dbb1d14b1b4406eca8ef9478e8de312ba0cfe (opens in a new tab)
- git.kernel.org/stable/c/c8f256dc849205ccb2bd78bd99a3497b972b44e0 (opens in a new tab)
- git.kernel.org/stable/c/0d75f2c1d0764efa756ad9c1e078d8c09ea8fc1f (opens in a new tab)
- git.kernel.org/stable/c/b8a39a09ae4eaae04309e1e38ed6a1101d967496 (opens in a new tab)