{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99167","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.398Z","datePublished":"2026-10-28T10:35:18.850Z","dateUpdated":"2026-10-31T12:44:30.175Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-31T12:44:30.175Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fix use-after-free in __tcf_action_put()\n\n__tcf_action_put() decrements the reference count before decrementing the\nbinding count. Another thread can free the action between these operations,\ncausing the binding-count update to access freed memory. KASAN reports it\nas:\n\n  BUG: KASAN: slab-use-after-free in __tcf_action_put+0x327/0x340\n  Write of size 4 at addr ff11000000d46420 by task tc-put-pause/64\n\nHold the action IDR mutex across both counter updates and IDR removal,\nkeeping cleanup outside the lock."}],"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 - An attacker reaches the patched __tcf_action_put() through local NETLINK_ROUTE messages: sendmsg() -> rtnetlink_rcv_msg() -> tc_new_tfilter()/tc_del_tfilter() -> tcf_action_destroy(). No received network packet supplies the action release operation.\nAC:L - RTM_NEWTFILTER and RTM_DELTFILTER are unlocked for flower on clsact/ingress; the attacker can race a failing bind request's tcf_action_destroy() against deletion cleanup of the same indexed action. One put takes tcfa_refcnt 2->1 before tcfa_bindcnt while the other takes 1->0 and frees it, so both sides are attacker-controlled.\nPR:L - rtnetlink_rcv_msg() requires netlink_net_capable(skb, CAP_NET_ADMIN), but checks the user namespace owning the socket's network namespace. An unprivileged user can use unshare(CLONE_NEWUSER|CLONE_NEWNET) to obtain that capability in the new namespace and configure its clsact/flower objects.\nUI:N - After creating the namespace and TC objects, the attacker alone sends the racing RTM_NEWTFILTER and RTM_DELTFILTER messages; no victim action is required.\nS:U - __tcf_action_put() corrupts memory in the same host kernel that processes and authorizes the NETLINK_ROUTE requests; exploitation does not cross a VM or IOMMU security boundary.\nC:H - After free_tcf() queues p for reclamation through kfree_rcu(), the stale path retains p and later accesses the reclaimed tcfa_bindcnt slot. Action-heap grooming can turn corruption of a replacement object into control-flow execution and arbitrary kernel-memory disclosure.\nI:H - atomic_dec(&p->tcfa_bindcnt) performs a 32-bit write after the tc_action allocation has been reclaimed; spraying a same-cache replacement can corrupt its refcount, length, or control data and enable kernel code execution or arbitrary modification.\nA:H - The reported KASAN slab-use-after-free is the stale atomic_dec() write in __tcf_action_put(); corrupting the replacement object can cause an oops or panic, and the attacker can repeatedly attempt the netlink race."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/act_api.c"],"versions":[{"version":"16af6067392c40e454e49eec834843ab03643d96","lessThan":"4d83a3fc03bc595dd39b79ad61288738fbb1f2ba","status":"affected","versionType":"git"},{"version":"16af6067392c40e454e49eec834843ab03643d96","lessThan":"fd01abed2568209f7daaf60e5ee68ae4a4744f48","status":"affected","versionType":"git"},{"version":"16af6067392c40e454e49eec834843ab03643d96","lessThan":"fcc7d734ceccfab8ec3398c5b34f8e775d459507","status":"affected","versionType":"git"},{"version":"16af6067392c40e454e49eec834843ab03643d96","lessThan":"fde33eb9955d819af282d5f5e84684eaec248291","status":"affected","versionType":"git"},{"version":"16af6067392c40e454e49eec834843ab03643d96","lessThan":"969ad6f2b266f383b44194d50d15631969b26222","status":"affected","versionType":"git"},{"version":"16af6067392c40e454e49eec834843ab03643d96","lessThan":"2465d27ef90de9105c2bffb6c35f8ce08918e642","status":"affected","versionType":"git"},{"version":"16af6067392c40e454e49eec834843ab03643d96","lessThan":"2e012e431aa271ef3c84206f48854f539c03bff0","status":"affected","versionType":"git"},{"version":"16af6067392c40e454e49eec834843ab03643d96","lessThan":"7b16eb911091aae237a8673da94e4dfb9cd21d54","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/act_api.c"],"versions":[{"version":"4.19","status":"affected"},{"version":"0","lessThan":"4.19","status":"unaffected","versionType":"semver"},{"version":"5.10.273","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.224","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.191","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.161","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.115","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.59","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.13","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","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":"4.19","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.6.161"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.18.59"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"7.3"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/4d83a3fc03bc595dd39b79ad61288738fbb1f2ba"},{"url":"https://git.kernel.org/stable/c/fd01abed2568209f7daaf60e5ee68ae4a4744f48"},{"url":"https://git.kernel.org/stable/c/fcc7d734ceccfab8ec3398c5b34f8e775d459507"},{"url":"https://git.kernel.org/stable/c/fde33eb9955d819af282d5f5e84684eaec248291"},{"url":"https://git.kernel.org/stable/c/969ad6f2b266f383b44194d50d15631969b26222"},{"url":"https://git.kernel.org/stable/c/2465d27ef90de9105c2bffb6c35f8ce08918e642"},{"url":"https://git.kernel.org/stable/c/2e012e431aa271ef3c84206f48854f539c03bff0"},{"url":"https://git.kernel.org/stable/c/7b16eb911091aae237a8673da94e4dfb9cd21d54"}],"title":"net/sched: fix use-after-free in __tcf_action_put()","x_generator":{"engine":"bippy-1.2.0"}}}}