CVE-2026-80890

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.

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EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/35c279113498d19a8734e2aae67b951b9b20f634 https://git.kernel.org/stable/c/61baa5020b0afb41bfd97f8f6ce5e336c4a4546e https://git.kernel.org/stable/c/817cffdbdbdf50e1f2b016599d1897de3ca54964 https://git.kernel.org/stable/c/9d8da8e0a9bce4a340af60dd0446bc7eb8d07587 https://git.kernel.org/stable/c/a0d1693923f41d6f49083aa2446686aed09d1d79 https://git.kernel.org/stable/c/c151daba0ceb1fb068a215b07de89fb1eb5f87bc https://git.kernel.org/stable/c/c68557a49e960dbcdede22c7a9b488603078b8b4 https://git.kernel.org/stable/c/f6e3cc296372accad4ee57405195021231ef4bcb

Frequently Asked Questions

What is CVE-2026-80890? +

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.

How do I check if I'm vulnerable to CVE-2026-80890? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.