CVE-2026-74587
In the Linux kernel, the following vulnerability has been resolved: sctp: fix use-after-free of cached ASCONF chunk addip_last_asconf caches the outstanding outbound ASCONF chunk.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In the Linux kernel, the following vulnerability has been resolved: sctp: fix use-after-free of cached ASCONF chunk addip_last_asconf caches the outstanding outbound ASCONF chunk. The normal ASCONF-ACK completion path releases the chunk and clears the pointer. However, sctp_asconf_queue_teardown() releases the cached chunk without clearing addip_last_asconf. During peer restart handling, sctp_sf_do_dupcook_a() queues SCTP_CMD_PURGE_ASCONF_QUEUE, which invokes sctp_asconf_queue_teardown() while the association remains alive and leaves the pointer dangling. A delayed authenticated ASCONF-ACK can then reach sctp_sf_do_asconf_ack(), which accesses the stale chunk and passes it to sctp_process_asconf_ack(), causing a use-after-free and a second release. Clearing the pointer exposes a race with T4 expiry. Peer restart handling queues the timer stop before the purge, but SCTP_CMD_TIMER_STOP uses timer_delete(), which does not wait for a callback already running on another CPU. Such a callback can reach sctp_sf_t4_timer_expire() after the purge and dereference NULL. Clear addip_last_asconf after releasing the cached chunk, and make sctp_sf_t4_timer_expire() consume a stale T4 expiry if no outstanding ASCONF remains.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.50% probability · 41th percentile
- CISA KEV
- Not listed
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/07daf4f9750104960a1d60831b2353c0d41f35fb
- https://git.kernel.org/stable/c/10459b03e2d9ee12435e96f587de4d4cacdbf435
- https://git.kernel.org/stable/c/179676f0166230c80053a392303485b37c93dd33
- https://git.kernel.org/stable/c/618b5c6d049896fcfabb91afc072954c92cb2693
- https://git.kernel.org/stable/c/8c283e7b56adce00193837f3311b06662466fb21
- https://git.kernel.org/stable/c/d949992bc3f00027a2c755e860a11950c75f6073
- https://git.kernel.org/stable/c/dc67d528c2fa939cec7fe3bf7f3089c8d281ca3d
- https://git.kernel.org/stable/c/e1bb114e09372fd6e03387ced9ef566da336ed6c
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.