Linux Kernel EUVD-2026-39315

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

sctp: validate embedded INIT chunk and address list lengths in cookie

sctp_unpack_cookie() only checked that the embedded INIT chunk length did not exceed the remaining cookie payload, but did not ensure that the INIT chunk is large enough to contain a complete INIT header.

A malformed COOKIE_ECHO can therefore carry a truncated INIT chunk whose length field is smaller than sizeof(struct sctp_init_chunk). Later, sctp_process_init() accesses INIT parameters unconditionally, which may lead to out-of-bounds reads.

In addition, raw_addr_list_len is not fully validated against the remaining cookie payload. When cookie authentication is disabled, an attacker can supply an oversized raw_addr_list_len and cause sctp_raw_to_bind_addrs() to read beyond the end of the cookie. The address parser also lacks sufficient bounds checks for parameter headers and lengths, allowing malformed address parameters to trigger out-of-bounds reads.

Fix this by:

• requiring the embedded INIT chunk length to be at least sizeof(struct

sctp_init_chunk);

• validating that the INIT chunk and raw address list together fit

within the cookie payload;

• verifying sufficient data exists for each address parameter header and

payload before parsing it.

Note that sctp_verify_init() must be called after sctp_unpack_cookie() and before sctp_process_init() when cookie authentication is disabled. This will be addressed in a separate patch.