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CVE-2026-31481

MEDIUMCVSS 5.5/10EPSS 0.11%

Last modified

CVE-2026-31481 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: tracing: Drain deferred trigger frees if kthread creation fails Boot-time trigger registration can fail before the trigger-data cleanup kthread exists. Deferring those frees until late init is fine, but the post-boot fallback must still drain the deferred list if kthread creation never succeeds. Otherwise, boot-deferred nodes can accumulate on trigger_data_free_list, later frees fall back to synchronously freeing only the current object, and the older queued entries are leaked forever. To trigger this, add the following to the kernel command line: trace_event=sched_switch trace_trigger=sched_switch.traceon,sched_switch.traceon The second traceon trigger will fail and be freed. EPSS estimates a 0.11% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: tracing: Drain deferred trigger frees if kthread creation fails Boot-time trigger registration can fail before the trigger-data cleanup kthread exists. Deferring those frees until late init is fine, but the post-boot fallback must still drain the deferred list if kthread creation never succeeds. Otherwise, boot-deferred nodes can accumulate on trigger_data_free_list, later frees fall back to synchronously freeing only the current object, and the older queued entries are leaked forever. To trigger this, add the following to the kernel command line: trace_event=sched_switch trace_trigger=sched_switch.traceon,sched_switch.traceon The second traceon trigger will fail and be freed. This triggers a NULL pointer dereference and crashes the kernel. Keep the deferred boot-time behavior, but when kthread creation fails, drain the whole queued list synchronously. Do the same in the late-init drain path so queued entries are not stranded there either.

Metrics

CVSS 3.1
5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
0.11%

1.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersionsUpdate
LinuxLinux Kernel>= 6.19.1, < 6.19.11—
LinuxLinux Kernel6.19—
LinuxLinux Kernel7.0Rc1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-31481?
In the Linux kernel, the following vulnerability has been resolved: tracing: Drain deferred trigger frees if kthread creation fails Boot-time trigger registration can fail before the trigger-data cleanup kthread exists. Deferring those frees until late init is fine, but the post-boot fallback must still drain the deferred list if kthread creation never succeeds. Otherwise, boot-deferred nodes can accumulate on trigger_data_free_list, later frees fall back to synchronously freeing only the current object, and the older queued entries are leaked forever. To trigger this, add the following to the kernel command line: trace_event=sched_switch trace_trigger=sched_switch.traceon,sched_switch.traceon The second traceon trigger will fail and be freed. This triggers a NULL pointer dereference and crashes the kernel. Keep the deferred boot-time behavior, but when kthread creation fails, drain the whole queued list synchronously. Do the same in the late-init drain path so queued entries are not stranded there either.
How severe is CVE-2026-31481?
CVE-2026-31481 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.11% probability of exploitation in the next 30 days.
How do I fix CVE-2026-31481?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST