{"api_version":"1","generated_at":"2026-11-01T09:39:22+00:00","cve":"CVE-2026-99167","urls":{"html":"https://cve.report/CVE-2026-99167","api":"https://cve.report/api/cve/CVE-2026-99167.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99167","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99167"},"summary":{"title":"net/sched: fix use-after-free in __tcf_action_put()","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-28 11:17:37","updated_at":"2026-10-31 13:17:58"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/4d83a3fc03bc595dd39b79ad61288738fbb1f2ba","name":"https://git.kernel.org/stable/c/4d83a3fc03bc595dd39b79ad61288738fbb1f2ba","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fcc7d734ceccfab8ec3398c5b34f8e775d459507","name":"https://git.kernel.org/stable/c/fcc7d734ceccfab8ec3398c5b34f8e775d459507","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2e012e431aa271ef3c84206f48854f539c03bff0","name":"https://git.kernel.org/stable/c/2e012e431aa271ef3c84206f48854f539c03bff0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fd01abed2568209f7daaf60e5ee68ae4a4744f48","name":"https://git.kernel.org/stable/c/fd01abed2568209f7daaf60e5ee68ae4a4744f48","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2465d27ef90de9105c2bffb6c35f8ce08918e642","name":"https://git.kernel.org/stable/c/2465d27ef90de9105c2bffb6c35f8ce08918e642","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/969ad6f2b266f383b44194d50d15631969b26222","name":"https://git.kernel.org/stable/c/969ad6f2b266f383b44194d50d15631969b26222","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7b16eb911091aae237a8673da94e4dfb9cd21d54","name":"https://git.kernel.org/stable/c/7b16eb911091aae237a8673da94e4dfb9cd21d54","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fde33eb9955d819af282d5f5e84684eaec248291","name":"https://git.kernel.org/stable/c/fde33eb9955d819af282d5f5e84684eaec248291","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99167","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99167","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 16af6067392c40e454e49eec834843ab03643d96 4d83a3fc03bc595dd39b79ad61288738fbb1f2ba git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 16af6067392c40e454e49eec834843ab03643d96 fd01abed2568209f7daaf60e5ee68ae4a4744f48 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 16af6067392c40e454e49eec834843ab03643d96 fcc7d734ceccfab8ec3398c5b34f8e775d459507 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 16af6067392c40e454e49eec834843ab03643d96 fde33eb9955d819af282d5f5e84684eaec248291 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.224 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.191 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.161 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.115 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.59 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.13 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"99167","cve":"CVE-2026-99167","epss":"0.001830000","percentile":"0.079290000","score_date":"2026-10-31","updated_at":"2026-11-01 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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":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"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."}]}],"providerMetadata":{"dateUpdated":"2026-10-31T12:44:30.175Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99167","datePublished":"2026-10-28T10:35:18.850Z","dateReserved":"2026-09-25T10:25:14.398Z","dateUpdated":"2026-10-31T12:44:30.175Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-28 11:17:37","lastModifiedDate":"2026-10-31 13:17:58","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"99167","Ordinal":"1","Title":"net/sched: fix use-after-free in __tcf_action_put()","CVE":"CVE-2026-99167","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99167","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"net/sched: fix use-after-free in __tcf_action_put()"}]}}}