CVE-2026-74752

In the Linux kernel, the following vulnerability has been resolved:

sctp: validate cookie AUTH state before use

When cookie authentication is disabled, COOKIE_ECHO restores fixed-size

AUTH fields directly from peer-controlled cookie bytes.  A forged RANDOM

length, HMAC list, or CHUNKS list can then reach association consumers

with lengths or identifiers that were never validated against the local

backing arrays.

A forged RANDOM length can cause out-of-bounds reads during key-vector

construction.  A forged HMAC identifier also caused a 32-byte write past

a zero-length AUTH chunk, providing a primitive for a local privilege

escalation chain.

Validate the cookie's RANDOM, HMACS, and CHUNKS parameters at the cookie

trust boundary before copying them into the association.  Reject invalid

types, malformed lengths, unsupported HMAC identifiers, HMAC lists

without SHA1, and forbidden chunk ids.