High [CVE-2026-68320] fix auth_chunk_list capacity check in sctp_auth_ep_add_chunkid

In the Linux kernel, the following vulnerability has been resolved: sctp: fix auth_chunk_list capacity check in sctp_auth_ep_add_chunkid sctp_auth_ep_add_chunkid() uses SCTP_NUM_CHUNK_TYPES (20) as the capacity limit for ep->auth_chunk_list, allowing it to hold up to 20 chunk entries (param_hdr.length up to 24).

However, the copy destination asoc->c.auth_chunks in struct sctp_cookie is only SCTP_AUTH_MAX_CHUNKS (16) entries (20 bytes). When more than 16 chunks are added, sctp_association_init() memcpy overflows the destination by up to 4 bytes.

Fix by using SCTP_AUTH_MAX_CHUNKS as the capacity limit, matching the destination capacity. A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) implementation.

This vulnerability occurs because the `sctp_auth_ep_add_chunkid` function allows more data to be written than the allocated buffer can hold during the initialization of an SCTP association. A remote attacker could potentially exploit this buffer overflow to cause memory corruption, leading to a denial of service or other unpredictable system behavior.

Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-120.

Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; and 3 more.