CVE-2026-74688

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

sctp: clear control chunk transport if it is being removed

sctpmakeheartbeatack() caches the destination transport in chunk->transport without taking a reference. When srcoutofasocok is enabled, the HEARTBEAT ACK may remain queued on controlchunk_list instead of being transmitted immediately.

If the peer transport is removed while the chunk is still queued, sctpassocrmpeer() drops the transport and schedules it for RCU freeing, but only clears cached transport pointers in outchunk_list. The queued control chunk therefore retains a dangling transport pointer.

Once an ASCONF_ACK clears the suppression and the queued control chunk is transmitted, SCTP dereferences the stale transport pointer, leading to a use-after-free.

Fix this by also clearing chunk->transport for queued control chunks in controlchunklist when removing the transport.