{ "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" } } } }