Bug 2541331 (CVE-2026-98130)

Summary: CVE-2026-98130 kernel: sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START
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: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) subsystem. A race condition exists when starting an SCTP timer, where the timer can expire before it is reset, resulting in improper reference counting for the connection association. An attacker could exploit this timing flaw during connection teardown to trigger a use-after-free condition, potentially causing a Denial of Service (DoS) or system crash.
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Description OSIDB Bzimport 2026-09-25 11:26:16 UTC 
In the Linux kernel, the following vulnerability has been resolved:

sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START

The SCTP_CMD_TIMER_START handler checks timer_pending() before calling
timer_reduce(). The timer can expire and detach between these operations,
causing timer_reduce() to rearm the timer without taking the association
reference required for the newly armed timer.

The timer callback later unconditionally drops its association reference,
which can leave the association reference count unbalanced and result in
use-after-free during association teardown.

Use the return value of timer_reduce() to determine whether the timer was
actually armed. Take the association reference only when timer_reduce()
successfully starts a new timer, closing the race between checking the
timer state and rearming it.

This issue was reported by Nico Yip (@_cyeaa_) working with TrendAI Zero
Day Initiative.
Comment 1 Keith Grant 2026-09-28 14:11:31 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98130.mbox