CVE-2026-74688: sctp: clear control chunk transport if it is being removed

Published Aug 22, 2026

Updated

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 controlchunklist 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 outchunklist. The queued control chunk therefore retains a dangling transport pointer.

Once an ASCONFACK 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.

Affected Software

1 affected component

Linux Linux kernel

Event History

Aug 22, 2026

CVE Published

via MITRE·03:32 PM

Data Sourced

via MITRE·03:32 PM

Description

Data Sourced

via NVD·04:16 PM

Description

Frequently Asked Questions

Which configurations are exposed to this condition?

The vulnerable path requires SCTP with src_out_of_asoc_ok enabled. The provided information does not state whether that setting is enabled by default.

What sequence is needed to trigger the use-after-free?

A HEARTBEAT ACK must remain queued on the control chunk list while its peer transport is removed. An ASCONF_ACK must later clear the suppression and cause the queued control chunk to be sent, at which point the stale transport pointer can be dereferenced.

How can I verify that a kernel contains the fix?

No affected or fixed kernel versions are provided. Verify that the SCTP peer-transport removal path clears chunk->transport for queued entries in control_chunk_list, in addition to entries in out_chunk_list.

CVE-2026-74688: sctp: clear control chunk transport if it is being removed

Affected Software

Event History

Frequently Asked Questions

Which configurations are exposed to this condition?

What sequence is needed to trigger the use-after-free?

How can I verify that a kernel contains the fix?

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Frequently Asked Questions

Which configurations are exposed to this condition?

What sequence is needed to trigger the use-after-free?

How can I verify that a kernel contains the fix?