{"id":"CVE-2026-31665","summary":"netfilter: nft_ct: fix use-after-free in timeout object destroy","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_ct: fix use-after-free in timeout object destroy\n\nnft_ct_timeout_obj_destroy() frees the timeout object with kfree()\nimmediately after nf_ct_untimeout(), without waiting for an RCU grace\nperiod. Concurrent packet processing on other CPUs may still hold\nRCU-protected references to the timeout object obtained via\nrcu_dereference() in nf_ct_timeout_data().\n\nAdd an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer\nfreeing until after an RCU grace period, matching the approach already\nused in nfnetlink_cttimeout.c.\n\nKASAN report:\n BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0\n Read of size 4 at addr ffff8881035fe19c by task exploit/80\n\n Call Trace:\n  nf_conntrack_tcp_packet+0x1381/0x29d0\n  nf_conntrack_in+0x612/0x8b0\n  nf_hook_slow+0x70/0x100\n  __ip_local_out+0x1b2/0x210\n  tcp_sendmsg_locked+0x722/0x1580\n  __sys_sendto+0x2d8/0x320\n\n Allocated by task 75:\n  nft_ct_timeout_obj_init+0xf6/0x290\n  nft_obj_init+0x107/0x1b0\n  nf_tables_newobj+0x680/0x9c0\n  nfnetlink_rcv_batch+0xc29/0xe00\n\n Freed by task 26:\n  nft_obj_destroy+0x3f/0xa0\n  nf_tables_trans_destroy_work+0x51c/0x5c0\n  process_one_work+0x2c4/0x5a0","modified":"2026-05-18T05:59:53.535094914Z","published":"2026-04-24T14:45:14.613Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31665.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/070abdf1b04325b21a20a2a0c39a2208af107275"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b42aca3660dc2627a29a38131597ca610dc451f9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c458fc1c278a65ad5381083121d39a479973ebed"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c581e5c8f2b59158f62efe61c1a3dc36189081ff"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d0983b48c10d1509fd795c155f8b1e832e1369ff"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f16fe84879a5280f05ebbcea593a189ba0f3e79a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f8dca15a1b190787bbd03285304b569631160eda"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31665.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31665"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7e0b2b57f01d183e1c84114f1f2287737358d748"},{"fixed":"c458fc1c278a65ad5381083121d39a479973ebed"},{"fixed":"c581e5c8f2b59158f62efe61c1a3dc36189081ff"},{"fixed":"f16fe84879a5280f05ebbcea593a189ba0f3e79a"},{"fixed":"070abdf1b04325b21a20a2a0c39a2208af107275"},{"fixed":"aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77"},{"fixed":"b42aca3660dc2627a29a38131597ca610dc451f9"},{"fixed":"d0983b48c10d1509fd795c155f8b1e832e1369ff"},{"fixed":"f8dca15a1b190787bbd03285304b569631160eda"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31665.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.19.0"},{"fixed":"5.10.253"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.203"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.169"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.135"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.82"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.23"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.13"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31665.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}