CVE-2026-80890 sctp: reject stale cookies with mismatched verification tags
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-80890?
CVE-2026-80890 is a vulnerability in Linux, published on 4 Sep 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
sctp: reject stale cookies with mismatched verification tags
sctp_unpack_cookie() skips cookie expiration checks whenever an association already exists. This is broader than the exception in RFC 9260 Section 5.2.4.
For an existing association, Section 5.2.4 permits an expired State Cookie only when both Verification Tags in the cookie match the current association. Otherwise, the packet SHOULD be discarded and a Stale Cookie ERROR MUST be sent.
The broad check lets an expired Action A restart cookie reach sctp_sf_do_dupcook_a(). In a runtime test with the default 60 second cookie lifetime, replaying such a cookie after 65 seconds returned a COOKIE-ACK and restarted the association.
Check cookie expiration unless both Verification Tags match. This preserves the Action D exception for a lost COOKIE ACK while rejecting expired cookies in all other cases.
Which versions are affected by CVE-2026-80890?
How do I fix CVE-2026-80890?
Upgrade to a fixed version.
Is CVE-2026-80890 being exploited?
There is no known exploitation of CVE-2026-80890 in the wild and no public exploit code.
Sources
Also known as AZL-99642, BELL-CVE-2026-80890, DEBIAN-CVE-2026-80890, GHSA-fqw8-ghgv-hjc2, UBUNTU-CVE-2026-80890.