Linux Kernel up to 7.2.3 io_uring io_waitid_cb cancel race condition

Summaryinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 7.2.3. The affected element is the function io_waitid_cb of the component io_uring. Such manipulation of the argument cancel leads to race condition. This vulnerability is uniquely identified as CVE-2026-81010. The attack can be launched remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.3 and classified as very critical. Affected by this issue is the function io_waitid_cb of the component io_uring. The manipulation of the argument cancel with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: io_uring/waitid: honor task_work cancellation io_waitid_cb() may run through the fallback task_work path when task_work_add() can no longer queue work to the originating task. The fallback runs from a kworker and io_uring marks such task work as canceled through tw.cancel. io_waitid_cb() currently ignores tw.cancel and calls __do_wait(). waitid is task-context dependent: __do_wait() performs child lookup relative to current, and the retry path also uses current->signal->wait_chldexit. If the callback runs from the fallback kworker, current is therefore not the task that submitted the request. Honor tw.cancel before entering __do_wait(). Complete the request with -ECANCELED and skip the siginfo copy, since canceled task work may run without the submitting task's userspace execution context. Keep the existing siginfo handling for normal waitid completion and explicit cancellation.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-81010 since 08/26/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/12/2026).

Upgrading to version 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch 7bc98e2de8c58a2bfaf0f540eb096a386ecfc96c/14572de82e5022899e5856008bc9cac97004a88c is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

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