CVE-2026-98130
Received Received - Intake

Linux kernel SCTP TOCTOU Race Condition Vulnerability

Publication date: 2026-09-25

Last updated on: 2026-09-25

Assigner: kernel.org

Description
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.

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Meta Information

Published
2026-09-25
Last Modified
2026-09-25
Generated
2026-09-25
AI Q&A
2026-09-25
EPSS Evaluated
N/A
NVD
CVE-2026-98130
EUVD
EUVD-2026-86961

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a race condition in the Linux kernel's SCTP implementation. The SCTP_CMD_TIMER_START handler checks if a timer is pending before reducing its duration. If the timer expires between these steps, timer_reduce() may rearm it without properly incrementing the association reference count. This leads to an unbalanced reference count and a potential use-after-free during association cleanup.

Detection Guidance

This vulnerability is specific to the Linux kernel's SCTP implementation and requires kernel-level inspection. Detection involves checking kernel logs for SCTP-related errors or crashes, or verifying if your kernel version includes the fix. Use commands like 'uname -a' to check kernel version and 'dmesg | grep sctp' to look for SCTP-related errors.

Impact Analysis

This vulnerability could cause system instability or crashes due to use-after-free errors during SCTP association teardown. Attackers might exploit this to trigger denial-of-service conditions or execute arbitrary code with kernel privileges if they can trigger the race condition.

Mitigation Strategies

Apply the latest kernel updates from your Linux distribution to ensure the fix is included. If immediate patching is not possible, consider disabling SCTP if not required by your system. Monitor kernel logs for SCTP-related crashes or errors as a potential sign of exploitation.

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