{"id":"CVE-2026-43027","state":"PUBLISHED","title":"netfilter: nf_conntrack_helper: pass helper to expect cleanup","description":"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->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)","publishedAt":"2026-05-01T14:15:28.521Z","updatedAt":"2026-10-15T01:18:41.165Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"5cf28d5c8dcbbe8af6d3b145babe491906d7bad1","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"504ba4168466c91210c45acdc332479cfd5f2da6","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"dc1739eff48e34cc71d4e2f03715493fbcebd8af","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"2cf2737c85a2ba2b52024dafe68ffad2676f97be","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"2c16e4d64dd91227742dfe196a3e7b0568bef65a","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"620f3d14c1ef51d425060a3056ad8dbae8f998a3","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"90bd7e8501349db3006d21fbc09df9ffcb172965","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"a242a9ae58aa46ff7dae51ce64150a93957abe65","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_helper.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.14","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.168","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.134","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.81","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.22","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.12","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_helper.c"]}],"references":["https://git.kernel.org/stable/c/5cf28d5c8dcbbe8af6d3b145babe491906d7bad1","https://git.kernel.org/stable/c/504ba4168466c91210c45acdc332479cfd5f2da6","https://git.kernel.org/stable/c/dc1739eff48e34cc71d4e2f03715493fbcebd8af","https://git.kernel.org/stable/c/2cf2737c85a2ba2b52024dafe68ffad2676f97be","https://git.kernel.org/stable/c/2c16e4d64dd91227742dfe196a3e7b0568bef65a","https://git.kernel.org/stable/c/620f3d14c1ef51d425060a3056ad8dbae8f998a3","https://git.kernel.org/stable/c/90bd7e8501349db3006d21fbc09df9ffcb172965","https://git.kernel.org/stable/c/a242a9ae58aa46ff7dae51ce64150a93957abe65","https://cert-portal.siemens.com/productcert/html/ssa-082556.html","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43027.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43027","state":"PUBLISHED","datePublished":"2026-05-01T14:15:28.521Z","dateUpdated":"2026-10-15T01:18:41.165Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:55.976Z"},"containers":{"cna":{"title":"netfilter: nf_conntrack_helper: pass helper to expect cleanup","descriptions":[{"lang":"en","value":"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->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)"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"5cf28d5c8dcbbe8af6d3b145babe491906d7bad1","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"504ba4168466c91210c45acdc332479cfd5f2da6","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"dc1739eff48e34cc71d4e2f03715493fbcebd8af","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"2cf2737c85a2ba2b52024dafe68ffad2676f97be","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"2c16e4d64dd91227742dfe196a3e7b0568bef65a","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"620f3d14c1ef51d425060a3056ad8dbae8f998a3","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"90bd7e8501349db3006d21fbc09df9ffcb172965","versionType":"git"},{"version":"ac7b848390036dadd4351899d2a23748075916bd","status":"affected","lessThan":"a242a9ae58aa46ff7dae51ce64150a93957abe65","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_helper.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.14","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.168","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.134","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.81","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.22","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.12","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_helper.c"]}],"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"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:16:18.081Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"5.10.253"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"5.15.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.1.168"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.6.134"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.12.81"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.18.22"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.19.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"vendor":"Siemens","product":"SIMATIC 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