High [CVE-2026-53246] validate cached peer INIT chunk length in COOKIE_ECHO processing

In the Linux kernel, the following vulnerability has been resolved: sctp: validate cached peer INIT chunk length in COOKIE_ECHO processing When a listening SCTP server processes a COOKIE_ECHO chunk, the cached peer INIT chunk embedded after the cookie is parsed and its parameters are later walked by sctp_process_init() using sctp_walk_params().

However, the chunk header length of this cached INIT chunk was not validated against the remaining buffer in the COOKIE_ECHO payload. If the length field is inflated, the parameter walk can run beyond the actual received data, leading to out-of-bounds reads and potential memory corruption during later parameter handling (e.g.

STATE_COOKIE processing and kmemdup() copies). Add a bounds check in sctp_unpack_cookie() to ensure the cached INIT chunk length does not exceed the available data in the COOKIE_ECHO buffer before it is used.

A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) implementation. A remote attacker could exploit this by sending a specially crafted COOKIE_ECHO chunk to a listening SCTP server.

The server's failure to properly validate the length of a cached peer INIT chunk within the COOKIE_ECHO payload could lead to out-of-bounds reads and memory corruption. This could result in a denial of service or potentially information disclosure.