{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64525", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.794Z", "datePublished": "2026-07-25T09:20:49.256Z", "dateUpdated": "2026-07-25T09:20:49.256Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-07-25T09:20:49.256Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: move policy_bydst RCU sync from per-netns .exit to .pre_exit\n\nThe struct pernet_operations docstring in include/net/net_namespace.h\nexplicitly warns against blocking RCU primitives in .exit handlers:\n\n Exit methods using blocking RCU primitives, such as\n synchronize_rcu(), should be implemented via exit_batch.\n [...]\n Please, avoid synchronize_rcu() at all, where it's possible.\n\n Note that a combination of pre_exit() and exit() can\n be used, since a synchronize_rcu() is guaranteed between\n the calls.\n\nxfrm_policy_fini() violates this: it calls synchronize_rcu() before\nfreeing the policy_bydst hash tables (so no RCU reader is mid-\ntraversal at free time), but runs from xfrm_net_ops.exit -- once per\nnamespace -- so a cleanup_net() of N namespaces pays N full RCU\ngrace periods serially.\n\nUse the documented pre_exit/exit split. Move the policy flush (and\nthe workqueue drains it depends on) into a new .pre_exit handler;\nxfrm_policy_fini() then runs in .exit and frees the hash tables\nafter the synchronize_rcu_expedited() that cleanup_net() guarantees\nbetween the two phases. Providing O(1) RCU grace periods per batch\ninstead of O(N).\n\nObserved on Linux 6.18 with a workload doing unshare(CLONE_NEWNET)\nat ~13/sec sustained: cleanup_net() and the netns_wq rescuer kthread\nboth stuck in xfrm_policy_fini()'s synchronize_rcu(), >300k struct\nnet accumulated in the cleanup queue, Percpu in /proc/meminfo climbed\nto 130+ GB on 256-CPU hosts, and memcg OOMs followed. setup_net and\n__put_net counts were balanced, ruling out a refcount leak." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/xfrm/xfrm_policy.c" ], "versions": [ { "version": "438b1f668ad58f46ce699bb48e4698a7839e3f9e", "lessThan": "bca6386dc08750fc7cdcbc7683473748ba3114b9", "status": "affected", "versionType": "git" }, { "version": "3733fce2871c9bca9dd18a1a23b1432ea215a094", "lessThan": "91cc13978ab0bc6f669139f53e7e613a860d10e0", "status": "affected", "versionType": "git" }, { "version": "069daad4f2ae9c5c108131995529d5f02392c446", "lessThan": "d14ae8ef88c2c6590e107db61b6adce148cec7b3", "status": "affected", "versionType": "git" }, { "version": "069daad4f2ae9c5c108131995529d5f02392c446", "lessThan": "3e52417318473782012b236d0325bf7d2266a597", "status": "affected", "versionType": "git" }, { "version": "b66920a3348c0f63ba18365248fa21fbf0b3a937", "status": "affected", "versionType": "git" }, { "version": "33a3149dd81a1e2f52b80ee1e0fc380b39f3d028", "status": "affected", "versionType": "git" }, { "version": "6.12.83", "lessThan": "6.12.93", "status": "affected", "versionType": "semver" }, { "version": "6.18.24", "lessThan": "6.18.35", "status": "affected", "versionType": "semver" }, { "version": "6.6.136", "lessThan": "6.7", "status": "affected", "versionType": "semver" }, { "version": "6.19.14", "lessThan": "6.20", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/xfrm/xfrm_policy.c" ], "versions": [ { "version": "7.0", "status": "affected" }, { "version": "0", "lessThan": "7.0", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.83", "versionEndExcluding": "6.12.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18.24", "versionEndExcluding": "6.18.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.1" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.136" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19.14" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/bca6386dc08750fc7cdcbc7683473748ba3114b9" }, { "url": "https://git.kernel.org/stable/c/91cc13978ab0bc6f669139f53e7e613a860d10e0" }, { "url": "https://git.kernel.org/stable/c/d14ae8ef88c2c6590e107db61b6adce148cec7b3" }, { "url": "https://git.kernel.org/stable/c/3e52417318473782012b236d0325bf7d2266a597" } ], "title": "xfrm: move policy_bydst RCU sync from per-netns .exit to .pre_exit", "x_generator": { "engine": "bippy-1.2.0" } } } }