CVE-2026-74587
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
In the Linux kernel, the SCTP protocol has a use-after-free vulnerability in the ASCONF mechanism. The cached ASCONF chunk is not properly cleared after release, leading to access to stale memory. The fix clears the addip_last_asconf pointer after release and protects against a race with T4 expiry.
Risk Assessment
Potential remote code execution or system crash via crafted SCTP packets. The vulnerability could be exploited to compromise data confidentiality and integrity.
Recommendation
Apply the Linux kernel patch for CVE-2026-74587. Restrict access to SCTP services to trusted networks only.
Original NVD description (English source)
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.