CVE-2026-74688
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.
CSIRTS triage
- What
- SCTP control chunk processing does not clear the transport pointer when the transport is being removed, causing use-after-free.
- Who is affected
- Systems using SCTP protocol with active connections during transport removal.
- Urgency
- Medium priority; CVSS 5.9 indicates moderate severity; not currently exploited.
- Action
- Apply kernel patch to clear control chunk transport during removal or update to patched kernel version.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.50% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 41% of all EPSS-scored CVEs.
Advisory coverage (2)
- criticalCVE-2026-74688: In the Linux kernel, the following vulnerability has been resolved: sctp: clear control chunk …nvd · 2026-08-22
- mediumCVE-2026-74688: sctp: clear control chunk transport if it is being removedmsrc · 2026-08-11
External references
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