PatchTheCVECVE-2026-23321: In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: in-kernel: always mark signal+
CVE-2026-23321 is a medium-severity flaw (CVSS 5.5) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: in-kernel: always mark signal+subflow endp as used Syzkaller managed to find a combination of actions that was generating this warning: msk->pm.local_addr_used == 0 WARNING: net/mptcp/pm_kernel.c:1071 at __mark_subflow_endp_available net/mptcp/pm_kernel.c:1071 [inline], CPU#1: syz.2.17/961 WARNING: net/mptcp/pm_kernel.c:1071 at mptcp_nl_remove_subflow_and_sign
Why this priority
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.5 (Medium) |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 0.1% (top 97%) |
| CISA exploited list | No |
| Published | 2026-03-25 |
| Last modified | 2026-10-15 |
Last updated 2026-10-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-23321?
linux kernel: upgrade to 6.1.167, 6.6.130, 6.11, 6.12.78, 6.18.17, 6.19.7. Exact commands for each OS are on this page.
Is CVE-2026-23321 being exploited?
CVE-2026-23321 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-23321 affect?
CVE-2026-23321 affects linux kernel. Severity is medium (CVSS 5.5). In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: in-kernel: always mark signal+subflow endp as used Syzkaller managed to find a combination of actions that was generating this warning: msk->pm.local_addr_u
How urgent is CVE-2026-23321?
Priority 25/100. On your watchlist
Software pages
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