CVE-2026-74688

/// Technical description

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

sctp: clear control chunk transport if it is being removed

sctp_make_heartbeat_ack() caches the destination transport in

chunk->transport without taking a reference. When src_out_of_asoc_ok is

enabled, the HEARTBEAT ACK may remain queued on control_chunk_list instead

of being transmitted immediately.

If the peer transport is removed while the chunk is still queued,

sctp_assoc_rm_peer() drops the transport and schedules it for RCU freeing,

but only clears cached transport pointers in out_chunk_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

control_chunk_list when removing the transport.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References