CVE-2026-52924
In 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.
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Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:Not supplied
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Technical explanation & impact
Technical root-cause details are not available in the current source record.
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Affected products and versions
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Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
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Vendor advisories, patches & exploit references
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