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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.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2026082600-CVE-2026-74752-6509@gregkh/T
A possible mitigation for systems that do not require SCTP may be to prevent the SCTP kernel module from loading: echo 'install sctp /bin/false' > /etc/modprobe.d/disable-sctp.conf If the module is already loaded and SCTP is not in use: modprobe -r sctp RHEL kernels build SCTP as a module (`CONFIG_IP_SCTP=m`), so disabling the `sctp` module should prevent the vulnerable SCTP code path from being reachable. This mitigation is only suitable for systems that do not require SCTP.