sctp: purge outqueue on stale COOKIE-ECHO handling

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Summary

CVECVE-2026-52924
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-24 08:16:22 UTC
Updated2026-06-24 08:16:22 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: sctp: purge outqueue on stale COOKIE-ECHO handling sctp_stream_update() is only invoked when the association is moved into COOKIE_WAIT during association setup/reconfiguration. In this path, the outbound stream scheduler state (stream->out_curr) is expected to be clean, since no user data should have been transmitted yet unless the state machine has already partially progressed. However, a corner case exists in sctp_sf_do_5_2_6_stale(): when a Stale Cookie ERROR is received, the association is rolled back from COOKIE_ECHOED to COOKIE_WAIT. In this scenario, user data may already have been queued and even bundled with the COOKIE-ECHO chunk. During the rollback, sctp_stream_update() frees the old stream table and installs a new one, but it does not invalidate stream->out_curr. As a result, out_curr may still point to a freed sctp_stream_out entry from the previous stream state. Later, SCTP scheduler dequeue paths (FCFS, RR, PRIO, etc.) rely on stream->out_curr->ext, which can lead to use-after-free once the old stream state has been released via sctp_stream_free(). This results in crashes such as (reported by Yuqi): BUG: KASAN: slab-use-after-free in sctp_sched_fcfs_dequeue+0x13a/0x140 Read of size 8 at addr ff1100004d4d3208 by task mini_poc/9312 CPU: 1 UID: 1001 PID: 9312 Comm: mini_poc Not tainted 7.1.0-rc1-00305-gbd3a4795d574 #5 PREEMPT(full) sctp_sched_fcfs_dequeue+0x13a/0x140 sctp_outq_flush+0x1603/0x33e0 sctp_do_sm+0x31c9/0x5d30 sctp_assoc_bh_rcv+0x392/0x6f0 sctp_inq_push+0x1db/0x270 sctp_rcv+0x138d/0x3c10 Fix this by fully purging the association outqueue when handling the Stale Cookie case. This ensures all pending transmit and retransmit state is dropped, and any scheduler cached pointers are invalidated, making it safe to rebuild stream state during COOKIE_WAIT restart. Updating only stream->out_curr would be insufficient, since queued and retransmittable data would still reference the old stream state and trigger later use-after-free in dequeue paths.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 84b7a319105db2f917ccdcf502bdc866082b1285 git Not specified
CNA Linux Linux affected 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 f46e1d1a758878f0d22c4fbbd1bf42bb7165d1e8 git Not specified
CNA Linux Linux affected 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 3c0741a441a7df7099d7ca6a64a6a0de09c677c8 git Not specified
CNA Linux Linux affected 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 2afc9e684dc7fecf73db1edc937ebbc47b4b68dc git Not specified
CNA Linux Linux affected 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 1d4652f677906a64487c13f9ace54b0eb263b5d0 git Not specified
CNA Linux Linux affected 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 a6207349e703cfc04756a4d16dec9176135813a5 git Not specified
CNA Linux Linux affected 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 83ade59e5da365f4bf8bce72c5a38774202b442f git Not specified
CNA Linux Linux affected 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 e374b22e9b07b72a25909621464ff74096151bfb git Not specified
CNA Linux Linux affected 4.15 Not specified
CNA Linux Linux unaffected 4.15 semver Not specified
CNA Linux Linux unaffected 5.10.259 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.210 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.176 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.143 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.94 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.36 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.13 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/83ade59e5da365f4bf8bce72c5a38774202b442f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a6207349e703cfc04756a4d16dec9176135813a5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/84b7a319105db2f917ccdcf502bdc866082b1285 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e374b22e9b07b72a25909621464ff74096151bfb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1d4652f677906a64487c13f9ace54b0eb263b5d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f46e1d1a758878f0d22c4fbbd1bf42bb7165d1e8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2afc9e684dc7fecf73db1edc937ebbc47b4b68dc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3c0741a441a7df7099d7ca6a64a6a0de09c677c8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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