{"id":"CVE-2026-43027","summary":"netfilter: nf_conntrack_helper: pass helper to expect cleanup","details":"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 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-\u003ehelper,\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)","modified":"2026-05-18T06:00:12.202800401Z","published":"2026-05-01T14:15:28.521Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43027.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2c16e4d64dd91227742dfe196a3e7b0568bef65a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2cf2737c85a2ba2b52024dafe68ffad2676f97be"},{"type":"WEB","url":"https://git.kernel.org/stable/c/504ba4168466c91210c45acdc332479cfd5f2da6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5cf28d5c8dcbbe8af6d3b145babe491906d7bad1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/620f3d14c1ef51d425060a3056ad8dbae8f998a3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/90bd7e8501349db3006d21fbc09df9ffcb172965"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a242a9ae58aa46ff7dae51ce64150a93957abe65"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dc1739eff48e34cc71d4e2f03715493fbcebd8af"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43027.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-43027"},{"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":"ac7b848390036dadd4351899d2a23748075916bd"},{"fixed":"5cf28d5c8dcbbe8af6d3b145babe491906d7bad1"},{"fixed":"504ba4168466c91210c45acdc332479cfd5f2da6"},{"fixed":"dc1739eff48e34cc71d4e2f03715493fbcebd8af"},{"fixed":"2cf2737c85a2ba2b52024dafe68ffad2676f97be"},{"fixed":"2c16e4d64dd91227742dfe196a3e7b0568bef65a"},{"fixed":"620f3d14c1ef51d425060a3056ad8dbae8f998a3"},{"fixed":"90bd7e8501349db3006d21fbc09df9ffcb172965"},{"fixed":"a242a9ae58aa46ff7dae51ce64150a93957abe65"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-43027.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.14.0"},{"fixed":"5.10.253"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.203"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.168"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.134"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.81"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.22"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.12"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-43027.json"}}],"schema_version":"1.7.5"}