Bug 2492108 (CVE-2026-52929)

Summary: CVE-2026-52929 kernel: sctp: stream: fully roll back denied add-stream state
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) stream handling. When an attempt to add outgoing streams is denied, the system fails to fully roll back the associated state. This incomplete rollback can leave behind stale stream metadata, which a subsequent stream re-addition can then reuse. This can lead to a null-pointer dereference, potentially causing a system crash and resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-06-24 08:02:20 UTC 
In the Linux kernel, the following vulnerability has been resolved:

sctp: stream: fully roll back denied add-stream state

When ADD_OUT_STREAMS is denied, SCTP only shrinks the queued chunks and
then lowers outcnt. That leaves removed stream metadata behind, so a
later re-add can reuse a stale ext and hit a null-pointer dereference in
the scheduler get path.

Fix the rollback by tearing down the removed stream state the same way
other stream resizes do. Unschedule the current scheduler state, drop
the removed stream ext state with sctp_stream_outq_migrate(), and then
reschedule the remaining streams.

This keeps scheduler-private RR/FC/PRIO lists consistent while fully
rolling back denied outgoing stream additions.
Comment 1 Keith Grant 2026-06-24 14:57:34 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062432-CVE-2026-52929-63ee@gregkh/T