{"id":"CVE-2026-23458","summary":"netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()\n\nctnetlink_dump_exp_ct() stores a conntrack pointer in cb-\u003edata for the\nnetlink dump callback ctnetlink_exp_ct_dump_table(), but drops the\nconntrack reference immediately after netlink_dump_start().  When the\ndump spans multiple rounds, the second recvmsg() triggers the dump\ncallback which dereferences the now-freed conntrack via nfct_help(ct),\nleading to a use-after-free on ct-\u003eext.\n\nThe bug is that the netlink_dump_control has no .start or .done\ncallbacks to manage the conntrack reference across dump rounds.  Other\ndump functions in the same file (e.g. ctnetlink_get_conntrack) properly\nuse .start/.done callbacks for this purpose.\n\nFix this by adding .start and .done callbacks that hold and release the\nconntrack reference for the duration of the dump, and move the\nnfct_help() call after the cb-\u003eargs[0] early-return check in the dump\ncallback to avoid dereferencing ct-\u003eext unnecessarily.\n\n BUG: KASAN: slab-use-after-free in ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n Read of size 8 at addr ffff88810597ebf0 by task ctnetlink_poc/133\n\n CPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc Not tainted 7.0.0-rc2+ #3 PREEMPTLAZY\n Call Trace:\n  \u003cTASK\u003e\n  ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n  netlink_dump+0x333/0x880\n  netlink_recvmsg+0x3e2/0x4b0\n  ? aa_sk_perm+0x184/0x450\n  sock_recvmsg+0xde/0xf0\n\n Allocated by task 133:\n  kmem_cache_alloc_noprof+0x134/0x440\n  __nf_conntrack_alloc+0xa8/0x2b0\n  ctnetlink_create_conntrack+0xa1/0x900\n  ctnetlink_new_conntrack+0x3cf/0x7d0\n  nfnetlink_rcv_msg+0x48e/0x510\n  netlink_rcv_skb+0xc9/0x1f0\n  nfnetlink_rcv+0xdb/0x220\n  netlink_unicast+0x3ec/0x590\n  netlink_sendmsg+0x397/0x690\n  __sys_sendmsg+0xf4/0x180\n\n Freed by task 0:\n  slab_free_after_rcu_debug+0xad/0x1e0\n  rcu_core+0x5c3/0x9c0","modified":"2026-05-13T03:51:38.844105984Z","published":"2026-04-03T15:15:39.041Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23458.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5cb81eeda909dbb2def209dd10636b51549a3f8a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9821b47f669eb82791fa0b1a6ebaf9aa219bea72"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bdf2724eefd4455a66863abb025bab8d3aa98c57"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cd541f15b60e2257441398cf495d978f816d09f8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d8cd0efbccc5cfb0a80da744a7da76e1333ab925"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f025171feef2ac65663d7986f1d5ff0c28d6b2a9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f04cc86d59906513d2d62183b882966fc0ae0390"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23458.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23458"},{"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":"e844a928431fa8f1359d1f4f2cef53d9b446bf52"},{"fixed":"d8cd0efbccc5cfb0a80da744a7da76e1333ab925"},{"fixed":"9821b47f669eb82791fa0b1a6ebaf9aa219bea72"},{"fixed":"bdf2724eefd4455a66863abb025bab8d3aa98c57"},{"fixed":"f04cc86d59906513d2d62183b882966fc0ae0390"},{"fixed":"f025171feef2ac65663d7986f1d5ff0c28d6b2a9"},{"fixed":"04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56"},{"fixed":"cd541f15b60e2257441398cf495d978f816d09f8"},{"fixed":"5cb81eeda909dbb2def209dd10636b51549a3f8a"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23458.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.10.0"},{"fixed":"5.10.253"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.203"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.167"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.130"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.78"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.20"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23458.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"}]}