CVE-2026-74587: Linux Vulnerability

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.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= a000c01e60e40e15304ffe48fff051d17a7bea91, < 10459b03e2d9ee12435e96f587de4d4cacdbf435; >= a000c01e60e40e15304ffe48fff051d17a7bea91, < e1bb114e09372fd6e03387ced9ef566da336ed6c; >= a000c01e60e40e15304ffe48fff051d17a7bea91, < 179676f0166230c80053a392303485b37c93dd33; >= a000c01e60e40e15304ffe48fff051d17a7bea91, < dc67d528c2fa939cec7fe3bf7f3089c8d281ca3d; >= a000c01e60e40e15304ffe48fff051d17a7bea91, < 618b5c6d049896fcfabb91afc072954c92cb2693; >= a000c01e60e40e15304ffe48fff051d17a7bea91, < 07daf4f9750104960a1d60831b2353c0d41f35fb; >= a000c01e60e40e15304ffe48fff051d17a7bea91, < d949992bc3f00027a2c755e860a11950c75f6073; >= a000c01e60e40e15304ffe48fff051d17a7bea91, < 8c283e7b56adce00193837f3311b06662466fb21
Linux	Linux	3.0

References

Timeline

Published: Aug 22, 2026
Last Modified: Aug 22, 2026
Status: Received

Frequently Asked Questions

What is 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. 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.

How severe is CVE-2026-74587?

Severity scoring for CVE-2026-74587 is pending analysis.

How do I fix CVE-2026-74587?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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