{"id":"CVE-2026-23286","state":"PUBLISHED","title":"atm: lec: fix null-ptr-deref in lec_arp_clear_vccs","description":"In the Linux kernel, the following vulnerability has been resolved:\n\natm: lec: fix null-ptr-deref in lec_arp_clear_vccs\n\nsyzkaller reported a null-ptr-deref in lec_arp_clear_vccs().\nThis issue can be easily reproduced using the syzkaller reproducer.\n\nIn the ATM LANE (LAN Emulation) module, the same atm_vcc can be shared by\nmultiple lec_arp_table entries (e.g., via entry->vcc or entry->recv_vcc).\nWhen the underlying VCC is closed, lec_vcc_close() iterates over all\nARP entries and calls lec_arp_clear_vccs() for each matched entry.\n\nFor example, when lec_vcc_close() iterates through the hlists in\npriv->lec_arp_empty_ones or other ARP tables:\n\n1. In the first iteration, for the first matched ARP entry sharing the VCC,\nlec_arp_clear_vccs() frees the associated vpriv (which is vcc->user_back)\nand sets vcc->user_back to NULL.\n2. In the second iteration, for the next matched ARP entry sharing the same\nVCC, lec_arp_clear_vccs() is called again. It obtains a NULL vpriv from\nvcc->user_back (via LEC_VCC_PRIV(vcc)) and then attempts to dereference it\nvia `vcc->pop = vpriv->old_pop`, leading to a null-ptr-deref crash.\n\nFix this by adding a null check for vpriv before dereferencing\nit. If vpriv is already NULL, it means the VCC has been cleared\nby a previous call, so we can safely skip the cleanup and just\nclear the entry's vcc/recv_vcc pointers.\n\nThe entire cleanup block (including vcc_release_async()) is placed inside\nthe vpriv guard because a NULL vpriv indicates the VCC has already been\nfully released by a prior iteration — repeating the teardown would\nredundantly set flags and trigger callbacks on an already-closing socket.\n\nThe Fixes tag points to the initial commit because the entry->vcc path has\nbeen vulnerable since the original code. The entry->recv_vcc path was later\nadded by commit 8d9f73c0ad2f (\"atm: fix a memory leak of vcc->user_back\")\nwith the same pattern, and both paths are fixed here.","publishedAt":"2026-03-25T10:26:45.531Z","updatedAt":"2026-05-11T22:03:55.973Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"8aff65a82b6389ec674d46e5b3d3ae6f07db5e3e","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"30c9744a989feb22cfbb84170eb0e038a7a2c1da","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"e9665986eb127290ceb535bd5d04d7a84265d94f","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"622062f24644b4536d3f437e0cf7a8c4bb421665","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2d9f57ea29a1f1772373b98a509b44d49fda609e","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"7ea92ab075d809ec8a96669a5ecf00f752057875","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"5f1cfea7921f5c126a441d973690eeba52677b64","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/atm/lec.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","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":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.77","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.17","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","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/atm/lec.c"]}],"references":["https://git.kernel.org/stable/c/8aff65a82b6389ec674d46e5b3d3ae6f07db5e3e","https://git.kernel.org/stable/c/30c9744a989feb22cfbb84170eb0e038a7a2c1da","https://git.kernel.org/stable/c/e9665986eb127290ceb535bd5d04d7a84265d94f","https://git.kernel.org/stable/c/622062f24644b4536d3f437e0cf7a8c4bb421665","https://git.kernel.org/stable/c/2d9f57ea29a1f1772373b98a509b44d49fda609e","https://git.kernel.org/stable/c/7ea92ab075d809ec8a96669a5ecf00f752057875","https://git.kernel.org/stable/c/5f1cfea7921f5c126a441d973690eeba52677b64","https://git.kernel.org/stable/c/101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:21.040Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/23xxx/CVE-2026-23286.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-23286","state":"PUBLISHED","datePublished":"2026-03-25T10:26:45.531Z","dateUpdated":"2026-05-11T22:03:55.973Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-01-13T15:37:45.992Z"},"containers":{"cna":{"title":"atm: lec: fix null-ptr-deref in lec_arp_clear_vccs","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\natm: lec: fix null-ptr-deref in lec_arp_clear_vccs\n\nsyzkaller reported a null-ptr-deref in lec_arp_clear_vccs().\nThis issue can be easily reproduced using the syzkaller reproducer.\n\nIn the ATM LANE (LAN Emulation) module, the same atm_vcc can be shared by\nmultiple lec_arp_table entries (e.g., via entry->vcc or entry->recv_vcc).\nWhen the underlying VCC is closed, lec_vcc_close() iterates over all\nARP entries and calls lec_arp_clear_vccs() for each matched entry.\n\nFor example, when lec_vcc_close() iterates through the hlists in\npriv->lec_arp_empty_ones or other ARP tables:\n\n1. In the first iteration, for the first matched ARP entry sharing the VCC,\nlec_arp_clear_vccs() frees the associated vpriv (which is vcc->user_back)\nand sets vcc->user_back to NULL.\n2. In the second iteration, for the next matched ARP entry sharing the same\nVCC, lec_arp_clear_vccs() is called again. It obtains a NULL vpriv from\nvcc->user_back (via LEC_VCC_PRIV(vcc)) and then attempts to dereference it\nvia `vcc->pop = vpriv->old_pop`, leading to a null-ptr-deref crash.\n\nFix this by adding a null check for vpriv before dereferencing\nit. If vpriv is already NULL, it means the VCC has been cleared\nby a previous call, so we can safely skip the cleanup and just\nclear the entry's vcc/recv_vcc pointers.\n\nThe entire cleanup block (including vcc_release_async()) is placed inside\nthe vpriv guard because a NULL vpriv indicates the VCC has already been\nfully released by a prior iteration — repeating the teardown would\nredundantly set flags and trigger callbacks on an already-closing socket.\n\nThe Fixes tag points to the initial commit because the entry->vcc path has\nbeen vulnerable since the original code. The entry->recv_vcc path was later\nadded by commit 8d9f73c0ad2f (\"atm: fix a memory leak of vcc->user_back\")\nwith the same pattern, and both paths are fixed here."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"8aff65a82b6389ec674d46e5b3d3ae6f07db5e3e","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"30c9744a989feb22cfbb84170eb0e038a7a2c1da","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"e9665986eb127290ceb535bd5d04d7a84265d94f","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"622062f24644b4536d3f437e0cf7a8c4bb421665","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2d9f57ea29a1f1772373b98a509b44d49fda609e","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"7ea92ab075d809ec8a96669a5ecf00f752057875","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"5f1cfea7921f5c126a441d973690eeba52677b64","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/atm/lec.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","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":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.77","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.17","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","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/atm/lec.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/8aff65a82b6389ec674d46e5b3d3ae6f07db5e3e"},{"url":"https://git.kernel.org/stable/c/30c9744a989feb22cfbb84170eb0e038a7a2c1da"},{"url":"https://git.kernel.org/stable/c/e9665986eb127290ceb535bd5d04d7a84265d94f"},{"url":"https://git.kernel.org/stable/c/622062f24644b4536d3f437e0cf7a8c4bb421665"},{"url":"https://git.kernel.org/stable/c/2d9f57ea29a1f1772373b98a509b44d49fda609e"},{"url":"https://git.kernel.org/stable/c/7ea92ab075d809ec8a96669a5ecf00f752057875"},{"url":"https://git.kernel.org/stable/c/5f1cfea7921f5c126a441d973690eeba52677b64"},{"url":"https://git.kernel.org/stable/c/101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:03:55.973Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.10.253"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.15.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.167"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.130"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.77"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.17"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.19.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}