{"id":"CVE-2026-43027","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_helper: pass helper to expect cleanup\n\nnf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy()\nto remove expectations belonging to…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_helper: pass helper to expect cleanup\n\nnf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy()\nto remove expectations belonging to…","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 >= 4.14, < 5.10.253","linux_kernel >= 5.11, < 5.15.203","linux_kernel >= 5.16, < 6.1.168","linux_kernel >= 6.2, < 6.6.134","linux_kernel >= 6.7, < 6.12.81","linux_kernel >= 6.13, < 6.18.22","linux_kernel >= 6.19, < 6.19.12","linux_kernel = 7.0"],"patched":["linux_kernel 6.19.12"],"published":"2026-05-01","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:19:25.647","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-43027","references":[{"url":"https://git.kernel.org/stable/c/2c16e4d64dd91227742dfe196a3e7b0568bef65a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2cf2737c85a2ba2b52024dafe68ffad2676f97be","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/504ba4168466c91210c45acdc332479cfd5f2da6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5cf28d5c8dcbbe8af6d3b145babe491906d7bad1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/620f3d14c1ef51d425060a3056ad8dbae8f998a3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/90bd7e8501349db3006d21fbc09df9ffcb172965","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a242a9ae58aa46ff7dae51ce64150a93957abe65","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/dc1739eff48e34cc71d4e2f03715493fbcebd8af","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"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00131,"epssPercentile":0.02697,"ingestedAt":"2026-09-08T15:33:26.989Z","slug":"CVE-2026-43027","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_helper: pass helper to expect cleanup\n\nnf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy()\nto remove expectations belonging to the helper being unregistered.\nHowever, it passes NULL instead of the helper pointer as the data\nargument, so expect_iter_me() never matches any expectation and all\nof them survive the cleanup.\n\nAfter unregister returns, nfnl_cthelper_del() frees the helper\nobject immediately.  Subsequent expectation dumps or packet-driven\ninit_conntrack() calls then dereference the freed exp->helper,\ncausing a use-after-free.\n\nPass the actual helper pointer so expectations referencing it are\nproperly destroyed before the helper object is freed.\n\n  BUG: KASAN: slab-use-after-free in string+0x38f/0x430\n  Read of size 1 at addr ffff888003b14d20 by task poc/103\n  Call Trace:\n   string+0x38f/0x430\n   vsnprintf+0x3cc/0x1170\n   seq_printf+0x17a/0x240\n   exp_seq_show+0x2e5/0x560\n   seq_read_iter+0x419/0x1280\n   proc_reg_read+0x1ac/0x270\n   vfs_read+0x179/0x930\n   ksys_read+0xef/0x1c0\n  Freed by task 103:\n  The buggy address is located 32 bytes inside of\n   freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)\n\n## Affected\n\n- `linux_kernel >= 4.14, < 5.10.253`\n- `linux_kernel >= 5.11, < 5.15.203`\n- `linux_kernel >= 5.16, < 6.1.168`\n- `linux_kernel >= 6.2, < 6.6.134`\n- `linux_kernel >= 6.7, < 6.12.81`\n- `linux_kernel >= 6.13, < 6.18.22`\n- `linux_kernel >= 6.19, < 6.19.12`\n- `linux_kernel = 7.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.19.12`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":221755,"id":"CVE-2026-43027","ts":1792035357848,"field":"cvss","old":null,"new":"7.8"},{"seq":221754,"id":"CVE-2026-43027","ts":1792035357848,"field":"severity","old":"none","new":"high"}]}