CVE-2026-23321: Linux kernel · mptcp: pm: in-kernel: always mark signal+subflow endp as used
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in c5c877e140e5f46023a74a51e577ce5edd0a4be7 : update Linux kernel when convenient.
Data as of 10 Nov 2026, 12:51 UTC
Rated Low by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- Patch
- Available – fixed in c5c877e140e5f46023a74a51e577ce5edd0a4be7, a64aa7db39392add5be09dffaedbf1f0ce5554df, 198824ccfa64ffebd918bf99c939bd8170a4a4d8 +6
Exploitation evidence
Disclosed: evidence found.
CVE published 25 Mar 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 10 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
The vulnerability has been fixed in Linux kernel versions 6.1.167, 6.6.130, 6.11, and corresponding commits. Users and administrators should upgrade to these or later kernel versions to remediate the issue. No additional mitigation actions are required beyond applying the official fixes.
Description
A vulnerability in the Linux kernel's Multipath TCP (MPTCP) path manager was identified and resolved. The issue involved improper marking of signal and subflow endpoints, which could trigger kernel warnings under specific conditions involving MPTCP subflows and endpoints. The flaw was discovered through fuzz testing (Syzkaller) and fixed in Linux kernel versions 6.1.167, 6.6.130, 6.11, and related commits.
References
- git.kernel.org/stable/c/c5c877e140e5f46023a74a51e577ce5edd0a4be7 (opens in a new tab)
- git.kernel.org/stable/c/05799c2f1ca5eb13d65764dda688d02021b65e06 (opens in a new tab)
- git.kernel.org/stable/c/67f34ab318807989b57dfdb0f79e2d4e57018290 (opens in a new tab)
- git.kernel.org/stable/c/a64aa7db39392add5be09dffaedbf1f0ce5554df (opens in a new tab)
- git.kernel.org/stable/c/198824ccfa64ffebd918bf99c939bd8170a4a4d8 (opens in a new tab)
- git.kernel.org/stable/c/579a752464a64cb5f9139102f0e6b90a1f595ceb (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)