Linux Kernel ovpn race condition

Summaryinfo

A vulnerability, which was classified as very critical, has been found in Linux Kernel. The impacted element is an unknown function of the component ovpn. This manipulation causes race condition. The identification of this vulnerability is CVE-2026-74750. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel (affected version unknown). It has been declared as very critical. Affected by this vulnerability is an unknown functionality of the component ovpn. The manipulation with an unknown input leads to a race condition vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ovpn: defer key slot crypto freeing to workqueue Key slots are released through a kref and the existing release path frees the AEAD transforms from an RCU callback. That is not safe for all crypto implementations: crypto_free_aead can sleep, for example when an async or hardware implementation has teardown work to complete. Use queue_rcu_work for key-slot release. This keeps the RCU grace period needed by lockless key-slot readers, but runs the actual crypto teardown from workqueue context where sleeping is allowed. Once the rcu_work callback runs, pre-existing RCU readers are gone, and the final kref put already proves that no transform user remains, so the worker can release the AEAD transforms and free the slot directly. The previous patch drains ovpn_wq during module exit, so queued key-slot teardown work cannot outlive module text.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-74750 since 08/15/2026. The exploitation appears to be easy. The attack can be launched remotely. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/26/2026).

Applying the patch 0f77ed5ee91946ea63e29f2e0ff9dc9e722d8da3 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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