Linux Kernel up to 7.0.10 srcu race condition

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 7.0.10. Affected by this vulnerability is the function call_srcu/synchronize_srcu/synchronize_srcu_expedited of the component srcu. The manipulation leads to race condition. This vulnerability is listed as CVE-2026-64211. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 7.0.10. This issue affects the function call_srcu/synchronize_srcu/synchronize_srcu_expedited of the component srcu. The manipulation 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 availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: srcu: Don't queue workqueue handlers to never-online CPUs While an srcu_struct structure is in the midst of switching from CPU-0 to all-CPUs state, it can attempt to invoke callbacks for CPUs that have never been online. Worse yet, it can attempt in invoke callbacks for CPUs that never will be online, even including imaginary CPUs not in cpu_possible_mask. This can cause hangs on s390, which is not set up to deal with workqueue handlers being scheduled on such CPUs. This commit therefore causes Tree SRCU to refrain from queueing workqueue handlers on CPUs that have not yet (and might never) come online. Because callbacks are not invoked on CPUs that have not been online, it is an error to invoke call_srcu(), synchronize_srcu(), or synchronize_srcu_expedited() on a CPU that is not yet fully online. However, it turns out to be less code to redirect the callbacks from too-early invocations of call_srcu() than to warn about such invocations. This commit therefore also redirects callbacks queued on not-yet-fully-online CPUs to the boot CPU.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-64211 since 07/19/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/24/2026).

Upgrading to version 7.0.11 eliminates this vulnerability. Applying the patch a4153538fcd2361c4e0039eb103265492d26044e/593889c401426004bd0ea0f6d4fcece728b03420 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.0.7
• 7.0.8
• 7.0.9
• 7.0.10

License

• open-source

Website

• Vendor: https://www.kernel.org/

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