{"id":"AZL-80607","summary":"CVE-2026-23286 affecting package kernel for versions less than 6.6.130.1-1","details":"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-\u003evcc or entry-\u003erecv_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-\u003elec_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-\u003euser_back)\nand sets vcc-\u003euser_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-\u003euser_back (via LEC_VCC_PRIV(vcc)) and then attempts to dereference it\nvia `vcc-\u003epop = vpriv-\u003eold_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-\u003evcc path has\nbeen vulnerable since the original code. The entry-\u003erecv_vcc path was later\nadded by commit 8d9f73c0ad2f (\"atm: fix a memory leak of vcc-\u003euser_back\")\nwith the same pattern, and both paths are fixed here.","modified":"2026-08-28T17:46:33.069304354Z","published":"2026-03-25T11:16:23Z","upstream":["CVE-2026-23286"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23286"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.130.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-80607.json"}}],"schema_version":"1.9.0"}