{"id":"CVE-2026-23286","title":"atm: lec: fix null-ptr-deref in lec_arp_clear_vccs","summary":"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…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8aff65a82b6389ec674d46e5b3d3ae6f07db5e3e","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 30c9744a989feb22cfbb84170eb0e038a7a2c1da","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < e9665986eb127290ceb535bd5d04d7a84265d94f","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 622062f24644b4536d3f437e0cf7a8c4bb421665","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2d9f57ea29a1f1772373b98a509b44d49fda609e","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7ea92ab075d809ec8a96669a5ecf00f752057875","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5f1cfea7921f5c126a441d973690eeba52677b64","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb","Linux 2.6.12"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T21:25:04.726747Z"},"published":"2026-03-25","updated":"2026-11-05","sourceUpdated":"2026-11-05T21:33:35.470Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23286","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"}],"tags":["cve.org"],"epss":0.0013,"epssPercentile":0.02647,"ingestedAt":"2026-11-05T22:38:32.109Z","slug":"CVE-2026-23286","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8aff65a82b6389ec674d46e5b3d3ae6f07db5e3e`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 30c9744a989feb22cfbb84170eb0e038a7a2c1da`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < e9665986eb127290ceb535bd5d04d7a84265d94f`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 622062f24644b4536d3f437e0cf7a8c4bb421665`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2d9f57ea29a1f1772373b98a509b44d49fda609e`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7ea92ab075d809ec8a96669a5ecf00f752057875`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5f1cfea7921f5c126a441d973690eeba52677b64`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb`\n- `Linux 2.6.12`\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":[]}