CVE-2026-74688 sctp: clear control chunk transport if it is being removed
A use-after-free in the Linux kernel SCTP implementation allows attackers to execute arbitrary code or escalate privileges when specific transport removal conditions occur.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74688?
CVE-2026-74688 is a critical use after free vulnerability in Linux, published on 22 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-74688?
How do I fix CVE-2026-74688?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-74688 being exploited?
There is no known exploitation of CVE-2026-74688 in the wild and no public exploit code.
Sources
Also known as AZL-97196, BELL-CVE-2026-74688, DEBIAN-CVE-2026-74688, GHSA-3vfv-7x6v-8jg6, UBUNTU-CVE-2026-74688.