{"id":"CVE-2026-23458","title":"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->data for the\nnetlink dump callback ctnetl…","summary":"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->data for the\nnetlink dump callback ctnetl…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.10, < 5.10.253","linux_kernel >= 5.11, < 5.15.203","linux_kernel >= 5.16, < 6.1.167","linux_kernel >= 6.2, < 6.6.130","linux_kernel >= 6.7, < 6.12.78","linux_kernel >= 6.13, < 6.18.20","linux_kernel >= 6.19, < 6.19.10","linux_kernel = 7.0"],"patched":["linux_kernel 6.19.10"],"published":"2026-04-03","updated":"2026-07-24","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-23458","references":[{"url":"https://git.kernel.org/stable/c/04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5cb81eeda909dbb2def209dd10636b51549a3f8a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9821b47f669eb82791fa0b1a6ebaf9aa219bea72","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bdf2724eefd4455a66863abb025bab8d3aa98c57","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cd541f15b60e2257441398cf495d978f816d09f8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d8cd0efbccc5cfb0a80da744a7da76e1333ab925","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f025171feef2ac65663d7986f1d5ff0c28d6b2a9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f04cc86d59906513d2d62183b882966fc0ae0390","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00131,"epssPercentile":0.03091,"ingestedAt":"2026-07-25T22:05:03.463Z","slug":"CVE-2026-23458","body":"## Overview\n\nIn 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->data 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->ext.\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->args[0] early-return check in the dump\ncallback to avoid dereferencing ct->ext 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  <TASK>\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\n\n## Affected\n\n- `linux_kernel >= 3.10, < 5.10.253`\n- `linux_kernel >= 5.11, < 5.15.203`\n- `linux_kernel >= 5.16, < 6.1.167`\n- `linux_kernel >= 6.2, < 6.6.130`\n- `linux_kernel >= 6.7, < 6.12.78`\n- `linux_kernel >= 6.13, < 6.18.20`\n- `linux_kernel >= 6.19, < 6.19.10`\n- `linux_kernel = 7.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.19.10`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}