{"id":"CVE-2026-43091","state":"PUBLISHED","title":"xfrm: Wait for RCU readers during policy netns exit","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: Wait for RCU readers during policy netns exit\n\nxfrm_policy_fini() frees the policy_bydst hash tables after flushing the\npolicy work items and deleting all policies, but it does not wait for\nconcurrent RCU readers to leave their read-side critical sections first.\n\nThe policy_bydst tables are published via rcu_assign_pointer() and are\nlooked up through rcu_dereference_check(), so netns teardown must also\nwait for an RCU grace period before freeing the table memory.\n\nFix this by adding synchronize_rcu() before freeing the policy hash tables.","publishedAt":"2026-05-06T07:40:23.955Z","updatedAt":"2026-10-30T12:24:55.188Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"b2faee12538b5b008eaef65a4201eb29cb5cefb3","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"b66920a3348c0f63ba18365248fa21fbf0b3a937","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"438b1f668ad58f46ce699bb48e4698a7839e3f9e","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"3733fce2871c9bca9dd18a1a23b1432ea215a094","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"33a3149dd81a1e2f52b80ee1e0fc380b39f3d028","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"069daad4f2ae9c5c108131995529d5f02392c446","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_policy.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.9","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.136","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.83","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.24","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.14","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_policy.c"]}],"references":["https://git.kernel.org/stable/c/b2faee12538b5b008eaef65a4201eb29cb5cefb3","https://git.kernel.org/stable/c/b66920a3348c0f63ba18365248fa21fbf0b3a937","https://git.kernel.org/stable/c/438b1f668ad58f46ce699bb48e4698a7839e3f9e","https://git.kernel.org/stable/c/3733fce2871c9bca9dd18a1a23b1432ea215a094","https://git.kernel.org/stable/c/33a3149dd81a1e2f52b80ee1e0fc380b39f3d028","https://git.kernel.org/stable/c/069daad4f2ae9c5c108131995529d5f02392c446"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-30T12:42:04.495Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43091.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43091","state":"PUBLISHED","datePublished":"2026-05-06T07:40:23.955Z","dateUpdated":"2026-10-30T12:24:55.188Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:55.984Z"},"containers":{"cna":{"title":"xfrm: Wait for RCU readers during policy netns exit","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: Wait for RCU readers during policy netns exit\n\nxfrm_policy_fini() frees the policy_bydst hash tables after flushing the\npolicy work items and deleting all policies, but it does not wait for\nconcurrent RCU readers to leave their read-side critical sections first.\n\nThe policy_bydst tables are published via rcu_assign_pointer() and are\nlooked up through rcu_dereference_check(), so netns teardown must also\nwait for an RCU grace period before freeing the table memory.\n\nFix this by adding synchronize_rcu() before freeing the policy hash tables."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"b2faee12538b5b008eaef65a4201eb29cb5cefb3","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"b66920a3348c0f63ba18365248fa21fbf0b3a937","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"438b1f668ad58f46ce699bb48e4698a7839e3f9e","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"3733fce2871c9bca9dd18a1a23b1432ea215a094","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"33a3149dd81a1e2f52b80ee1e0fc380b39f3d028","versionType":"git"},{"version":"e1e551bc56302b80ff930c966f9985095fb1b70d","status":"affected","lessThan":"069daad4f2ae9c5c108131995529d5f02392c446","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_policy.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.9","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.136","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.83","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.24","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.14","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_policy.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/b2faee12538b5b008eaef65a4201eb29cb5cefb3"},{"url":"https://git.kernel.org/stable/c/b66920a3348c0f63ba18365248fa21fbf0b3a937"},{"url":"https://git.kernel.org/stable/c/438b1f668ad58f46ce699bb48e4698a7839e3f9e"},{"url":"https://git.kernel.org/stable/c/3733fce2871c9bca9dd18a1a23b1432ea215a094"},{"url":"https://git.kernel.org/stable/c/33a3149dd81a1e2f52b80ee1e0fc380b39f3d028"},{"url":"https://git.kernel.org/stable/c/069daad4f2ae9c5c108131995529d5f02392c446"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path requires local control of a network namespace/XFRM policy state and concurrent namespace teardown; remote packets can exercise XFRM policy lookups, but a remote attacker cannot normally trigger the required netns exit.\nAC:L - The race is attacker-controllable by creating XFRM policies, generating policy lookups, and tearing down the namespace concurrently; no rare configuration or victim-controlled timing is required beyond winning a repeatable local race.\nPR:L - XFRM netlink operations require CAP_NET_ADMIN in the target network namespace, but an unprivileged local user can obtain that in a new user+network namespace on common userns-enabled systems.\nUI:N - No victim action is required once the local attacker can run code and issue the relevant namespace, netlink, and traffic operations.\nS:U - The impact is within the kernel security authority; this is a standard kernel memory-safety issue rather than a VM, IOMMU, or separate-scope escape.\nC:H - This is a use-after-free of an RCU-published XFRM policy hash table, and stale readers may dereference reallocated attacker-influenced memory during policy lookup.\nI:H - As a kernel UAF in a list traversal path that can reach policy object handling, the freed memory can plausibly be shaped into fake list/policy data and leveraged for kernel memory corruption.\nA:H - At minimum, dereferencing freed hash-table memory during packet or route policy lookup can trigger a kernel oops or panic, causing high availability impact."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:24:55.188Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.6.136"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.12.83"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.18.24"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.19.14"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-43091","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:14:31.928454Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","type":"CWE","description":"CWE-416 Use After Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:06:13.331Z"}}]}}}