CVE-2026-43091

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: Wait for RCU readers during policy netns exit xfrm_policy_fini() frees the policy_bydst hash tables after flushing the policy work items and deleting all policies, but it does not wait for concurrent RCU readers to leave their read-side critical sections first. The policy_bydst tables are published via rcu_assign_pointer() and are looked up through rcu_dereference_check(), so netns teardown must also wait for an RCU grace period before freeing the table memory. Fix this by adding synchronize_rcu() before freeing the policy hash tables.

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CVSS v3.1 Score

7.8

HIGH

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

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.02%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/069daad4f2ae9c5c108131995529d5f02392c446 https://git.kernel.org/stable/c/33a3149dd81a1e2f52b80ee1e0fc380b39f3d028 https://git.kernel.org/stable/c/3733fce2871c9bca9dd18a1a23b1432ea215a094 https://git.kernel.org/stable/c/438b1f668ad58f46ce699bb48e4698a7839e3f9e https://git.kernel.org/stable/c/b66920a3348c0f63ba18365248fa21fbf0b3a937

Frequently Asked Questions

What is CVE-2026-43091? +

In the Linux kernel, the following vulnerability has been resolved: xfrm: Wait for RCU readers during policy netns exit xfrm_policy_fini() frees the policy_bydst hash tables after flushing the policy work items and deleting all policies, but it does not wait for concurrent RCU readers to leave their read-side critical sections first. The policy_bydst tables are published via rcu_assign_pointer() and are looked up through rcu_dereference_check(), so netns teardown must also wait for an RCU grace period before freeing the table memory. Fix this by adding synchronize_rcu() before freeing the policy hash tables. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-43091? +

CVE-2026-43091 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-43091? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.