{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53264","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-06-09T07:44:35.395Z","datePublished":"2026-06-25T08:39:51.870Z","dateUpdated":"2026-08-05T12:34:41.215Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:34:41.215Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_api: use RCU with deferred freeing for action lifecycle\n\nWhen NEWTFILTER and DELFILTER are run concurrently it is possible to create a\nrace with an associated action.\n\nLet's illustrate with CPU0 running NEWTFILTER and CPU1 running DELFILTER:\n\n 0: mutex_lock() <-- holds the idr lock\n 0: rcu_read_lock()\n 0: p = idr_find(idr, index) <-- action p is valid (RCU protects IDR)\n 0: mutex_unlock() <-- releases the idr lock\n 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held\n 1: idr_remove(idr, index) <-- Action removed from IDR\n 1: mutex_unlock() <-- mutex released allowing us to delete the action\n 1: tcf_action_cleanup(p); kfree(p) <-- Kfrees p immediately, no deferral\n 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- ouch, UAF p points to freed memory\n\nThis patch fixes the race condition between NEWTFILTER and DELFILTER by\nadding struct rcu_head to tc_action used in the deferral and introducing a\ncall_rcu() in the delete path to defer the final kfree().\n\nNote: this is a revert of commit d7fb60b9cafb (\"net_sched: get rid of tcfa_rcu\")\nbut also modernization/simplification to directly use kfree_rcu().\n\nLet's illustrate the new restored code path:\n\n 0: rcu_read_lock()\n 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held\n 1: idr_remove(idr, index)\n 1: mutex_unlock()\n 1: call_rcu(&p->tcfa_rcu, tcf_action_rcu_free) <-- defer kfree after grace period\n 0: p = idr_find(idr, index)\n 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- fails, refcnt already 0\n 1: rcu_read_unlock() <-- release so freeing can run after grace period\n\nAfter CPU1 calls idr_remove(), the object is no longer reachable through the IDR.\nCPU0's subsequent idr_find() will return NULL, and even if it still held a\nstale pointer, the immediate kfree() is now deferred until after the RCU grace\nperiod, so no UAF can occur."}],"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 is reached through local rtnetlink `RTM_NEWTFILTER`/`RTM_DELTFILTER` traffic-control netlink messages, not by remote packet input.\nAC:L - The race is attacker-controlled because the same local actor can issue concurrent filter creation and deletion operations against the same action index. No external victim timing or rare environmental condition is required.\nPR:L - The operations require `CAP_NET_ADMIN` for non-GET rtnetlink messages, but traffic control is reachable with `CAP_NET_ADMIN` inside a user-created network namespace. Under the provided kernel guidance, this is Low privileges rather than High.\nUI:N - No victim interaction is needed; exploitation consists of the attacker sending crafted concurrent rtnetlink requests.\nS:U - The impact is within the kernel security authority and is a standard local kernel memory-corruption/privilege-escalation class issue. It does not cross a VM, IOMMU, or separate authorization scope boundary.\nC:H - The bug is a use-after-free of a `tc_action` object during action lookup/refcounting. A kernel heap UAF can be shaped into disclosure primitives, so confidentiality impact is High.\nI:H - The stale freed action pointer can be reused after heap reallocation and then modified/dereferenced through refcount, bind count, ops, and action lifecycle fields. This is memory corruption that can plausibly support arbitrary write or code execution, so integrity impact is High.\nA:H - Even without full exploitation, the UAF can dereference or mutate freed/reused kernel memory and can crash or oops the kernel. Availability impact is therefore High."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/act_api.h","net/sched/act_api.c"],"versions":[{"version":"d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da","lessThan":"98b2e40879abf0245be5a5b7af69e0f6ff524ac3","status":"affected","versionType":"git"},{"version":"d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da","lessThan":"18af5d2ef0c4f65787fd1280c8b23286b9f2a835","status":"affected","versionType":"git"},{"version":"d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da","lessThan":"1f1b98fea6b9ea30507d0f2fbff6750292d097e2","status":"affected","versionType":"git"},{"version":"d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da","lessThan":"8b136f18ac4b2ace5aaad3305b3f8a5d8165a009","status":"affected","versionType":"git"},{"version":"d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da","lessThan":"5dd51e09020c65aa53cf128e5e3517cd53b3c113","status":"affected","versionType":"git"},{"version":"d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da","lessThan":"b60e9391142e983fab2be53497aa8f71fdd09cd5","status":"affected","versionType":"git"},{"version":"d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da","lessThan":"91d105d2cbe002f9c7b43a6183adedc37e1da1f7","status":"affected","versionType":"git"},{"version":"d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da","lessThan":"5057e1aca011e51ef51498c940ef96f3d3e8a305","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/act_api.h","net/sched/act_api.c"],"versions":[{"version":"4.14","status":"affected"},{"version":"0","lessThan":"4.14","status":"unaffected","versionType":"semver"},{"version":"5.10.259","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.210","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.176","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.143","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.94","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.36","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.13","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":"4.14","versionEndExcluding":"5.10.259"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"5.15.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.6.143"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.12.94"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.18.36"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"7.0.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/98b2e40879abf0245be5a5b7af69e0f6ff524ac3"},{"url":"https://git.kernel.org/stable/c/18af5d2ef0c4f65787fd1280c8b23286b9f2a835"},{"url":"https://git.kernel.org/stable/c/1f1b98fea6b9ea30507d0f2fbff6750292d097e2"},{"url":"https://git.kernel.org/stable/c/8b136f18ac4b2ace5aaad3305b3f8a5d8165a009"},{"url":"https://git.kernel.org/stable/c/5dd51e09020c65aa53cf128e5e3517cd53b3c113"},{"url":"https://git.kernel.org/stable/c/b60e9391142e983fab2be53497aa8f71fdd09cd5"},{"url":"https://git.kernel.org/stable/c/91d105d2cbe002f9c7b43a6183adedc37e1da1f7"},{"url":"https://git.kernel.org/stable/c/5057e1aca011e51ef51498c940ef96f3d3e8a305"}],"title":"net/sched: act_api: use RCU with deferred freeing for action lifecycle","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"problemTypes":[{"descriptions":[{"type":"CWE","cweId":"CWE-416","lang":"en","description":"CWE-416 Use After Free"}]}],"references":[{"url":"https://starlabs.sg/blog/2026/07-when-ai-makes-0-days-feel-like-n-days/","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-29T03:55:26.363824Z","id":"CVE-2026-53264","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-07-29T18:15:51.295Z"}}]}}