Linux Kernel Vulnerability Affecting Policy Management

CVE-2026-43091

What is CVE-2026-43091?

The Linux kernel has a vulnerability in its policy management system where the xfrm_policy_fini() function fails to properly manage concurrent readers during the policy netns exit process. Specifically, it does not wait for all RCU (Read-Copy-Update) readers to complete their critical sections before freeing the policy_bydst hash tables. This oversight can lead to potential instability in kernel operations. To remedy this, a synchronize_rcu() call has been introduced to ensure that the hash tables are safely freed only after all readers have completed their operations, thereby enhancing the overall stability and security of the system.

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