{"id":"CVE-2026-43027","title":"netfilter: nf_conntrack_helper: pass helper to expect cleanup","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":"none","vendor":"Linux","product":"Linux","affected":["Linux >= ac7b848390036dadd4351899d2a23748075916bd < 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1","Linux >= ac7b848390036dadd4351899d2a23748075916bd < 504ba4168466c91210c45acdc332479cfd5f2da6","Linux >= ac7b848390036dadd4351899d2a23748075916bd < dc1739eff48e34cc71d4e2f03715493fbcebd8af","Linux >= ac7b848390036dadd4351899d2a23748075916bd < 2cf2737c85a2ba2b52024dafe68ffad2676f97be","Linux >= ac7b848390036dadd4351899d2a23748075916bd < 2c16e4d64dd91227742dfe196a3e7b0568bef65a","Linux >= ac7b848390036dadd4351899d2a23748075916bd < 620f3d14c1ef51d425060a3056ad8dbae8f998a3","Linux >= ac7b848390036dadd4351899d2a23748075916bd < 90bd7e8501349db3006d21fbc09df9ffcb172965","Linux >= ac7b848390036dadd4351899d2a23748075916bd < a242a9ae58aa46ff7dae51ce64150a93957abe65","Linux 4.14"],"published":"2026-05-01","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:48:27.805Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43027","references":[{"url":"https://git.kernel.org/stable/c/5cf28d5c8dcbbe8af6d3b145babe491906d7bad1"},{"url":"https://git.kernel.org/stable/c/504ba4168466c91210c45acdc332479cfd5f2da6"},{"url":"https://git.kernel.org/stable/c/dc1739eff48e34cc71d4e2f03715493fbcebd8af"},{"url":"https://git.kernel.org/stable/c/2cf2737c85a2ba2b52024dafe68ffad2676f97be"},{"url":"https://git.kernel.org/stable/c/2c16e4d64dd91227742dfe196a3e7b0568bef65a"},{"url":"https://git.kernel.org/stable/c/620f3d14c1ef51d425060a3056ad8dbae8f998a3"},{"url":"https://git.kernel.org/stable/c/90bd7e8501349db3006d21fbc09df9ffcb172965"},{"url":"https://git.kernel.org/stable/c/a242a9ae58aa46ff7dae51ce64150a93957abe65"}],"tags":["cve.org"],"epss":0.00131,"epssPercentile":0.03094,"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 >= ac7b848390036dadd4351899d2a23748075916bd < 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1`\n- `Linux >= ac7b848390036dadd4351899d2a23748075916bd < 504ba4168466c91210c45acdc332479cfd5f2da6`\n- `Linux >= ac7b848390036dadd4351899d2a23748075916bd < dc1739eff48e34cc71d4e2f03715493fbcebd8af`\n- `Linux >= ac7b848390036dadd4351899d2a23748075916bd < 2cf2737c85a2ba2b52024dafe68ffad2676f97be`\n- `Linux >= ac7b848390036dadd4351899d2a23748075916bd < 2c16e4d64dd91227742dfe196a3e7b0568bef65a`\n- `Linux >= ac7b848390036dadd4351899d2a23748075916bd < 620f3d14c1ef51d425060a3056ad8dbae8f998a3`\n- `Linux >= ac7b848390036dadd4351899d2a23748075916bd < 90bd7e8501349db3006d21fbc09df9ffcb172965`\n- `Linux >= ac7b848390036dadd4351899d2a23748075916bd < a242a9ae58aa46ff7dae51ce64150a93957abe65`\n- `Linux 4.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}