{"id":"CVE-2026-97609","summary":"netfilter: cttimeout: prevent UAF during module unload","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: cttimeout: prevent UAF during module unload\n\nnf_ct_set_timeout() protects the timeout hook dereference and policy lookup\nwith rcu_read_lock(). cttimeout_exit(), however, unregisters the per-net\noperations before it clears the hook.\n\nThis allows the following interleaving:\n\n  CPU 0                              CPU 1\n  cttimeout_exit()                   nf_ct_set_timeout()\n    unregister_pernet_subsys()         rcu_read_lock()\n      kfree(pernet)                     h = nf_ct_timeout_hook\n                                        h-\u003etimeout_find_get()\n                                          nfct_timeout_pernet()\n\nThe hook still points to ctnl_timeout_find_get() when CPU 1 looks up the\nalready freed per-net timeout list. KASAN reported:\n\n  BUG: KASAN: slab-use-after-free in ctnl_timeout_find_get\n  Read of size 8 by task poc/90\n  Call Trace:\n   ctnl_timeout_find_get+0x271/0x2a0 [nfnetlink_cttimeout]\n   nf_ct_set_timeout+0x7b/0x3c0\n   xt_ct_tg_check+0x724/0xb20\n   xt_check_target+0x234/0xa90\n   do_ipt_set_ctl+0x570/0x1270\n  Allocated by task 89:\n   __kmalloc_noprof+0x16e/0x460\n   ops_init+0x6d/0x420\n   register_pernet_operations+0x2f6/0x670\n  Freed by task 91:\n   kfree+0x131/0x390\n   ops_undo_list+0x3d4/0x730\n   unregister_pernet_operations+0x232/0x490\n   unregister_pernet_subsys+0x1c/0x30\n   cttimeout_exit+0x52/0x970 [nfnetlink_cttimeout]\n\nClear the hook and wait for existing readers before unregistering the\nper-net operations. This blocks new policy lookups and ensures readers that\nobserved the hook finish before the per-net storage is freed.","modified":"2026-09-26T03:48:36.495473845Z","published":"2026-09-25T10:22:19.627Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97609.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1f69c570a73f2dedf75ea5166d47622d5fa958c1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a7fdd86c386b7f7cc72a126389c2cdb55d035221"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fec9b1de0d02de8dafa3cc344bcb91cf28660643"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97609.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97609"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ebfbe67568a734a449203097b02c4ab884257535"},{"fixed":"a7fdd86c386b7f7cc72a126389c2cdb55d035221"},{"fixed":"1f69c570a73f2dedf75ea5166d47622d5fa958c1"},{"fixed":"fec9b1de0d02de8dafa3cc344bcb91cf28660643"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97609.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.13.0"},{"fixed":"6.18.53"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97609.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}