CVE-2026-74587

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> sctp: fix use-after-free of cached ASCONF chunk<br /> <br /> addip_last_asconf caches the outstanding outbound ASCONF chunk. The normal<br /> ASCONF-ACK completion path releases the chunk and clears the pointer.<br /> <br /> However, sctp_asconf_queue_teardown() releases the cached chunk without<br /> clearing addip_last_asconf. During peer restart handling,<br /> sctp_sf_do_dupcook_a() queues SCTP_CMD_PURGE_ASCONF_QUEUE, which invokes<br /> sctp_asconf_queue_teardown() while the association remains alive and leaves<br /> the pointer dangling.<br /> <br /> A delayed authenticated ASCONF-ACK can then reach sctp_sf_do_asconf_ack(),<br /> which accesses the stale chunk and passes it to sctp_process_asconf_ack(),<br /> causing a use-after-free and a second release.<br /> <br /> Clearing the pointer exposes a race with T4 expiry. Peer restart handling<br /> queues the timer stop before the purge, but SCTP_CMD_TIMER_STOP uses<br /> timer_delete(), which does not wait for a callback already running on<br /> another CPU. Such a callback can reach sctp_sf_t4_timer_expire() after<br /> the purge and dereference NULL.<br /> <br /> Clear addip_last_asconf after releasing the cached chunk, and make<br /> sctp_sf_t4_timer_expire() consume a stale T4 expiry if no outstanding<br /> ASCONF remains.