CVE-2026-53246sctp: validate cached peer INIT chunk length in COOKIE_ECHO processing

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/cc272185c9a9a4b7febc2de52eeaa3d00f19091e
• https://git.kernel.org/stable/c/edccbf3d63b0a3362bc916ea72edacc1e1ca456a
• https://git.kernel.org/stable/c/0861615c28de668669d748ef4eb913ea9262d13b