{"schema":"threatline.record/2","record":{"id":"CVE-2026-98122","aliases":[],"summary":"vxlan: mdb: Fix use-after-free in vxlan_mdb_remote_src_del()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: mdb: Fix use-after-free in vxlan_mdb_remote_src_del()\n\nvxlan_mdb_is_valid_source(), which validates MDBE_ATTR_SOURCE and every\nMDBE_ATTR_SRC_LIST member, accepts the all-zeros address.\n\nA source list is only accepted on a (*, G) entry, whose source is the\nall-zeros address, and for each member of the list an (S, G) entry is\nderived from it by substituting the source. Entries are keyed by a plain\nmemcmp() of struct vxlan_mdb_entry_key, so if MDBE_ATTR_SOURCE is present\nand holds the all-zeros address and the source list holds it as well, the\nderived (S, G) key is byte-identical to the (*, G) key and resolves to the\nsame entry. Omitting MDBE_ATTR_SOURCE is not equivalent, as the key is\nthen left with a zero address family.\n\nvxlan_mdb_remote_src_del() removes the forwarding entry of a source before\nfreeing the source entry:\n\n\tvxlan_mdb_remote_src_fwd_del(vxlan, group, remote, &ent->addr);\n\tvxlan_mdb_remote_src_entry_del(ent);\n\nWith the keys aliased, the first call deletes the remote of the entry that\nowns 'ent' instead of a separate (S, G) entry, and frees 'ent'. The second\ncall then runs on the freed entry, and its hlist_del() reads ->pprev and\n->next out of it and writes through them.\n\nAdding the (*, G) entry with NLM_F_REPLACE and no source list marks the\nall-zeros source for deletion and reaches this from the sweep at the end\nof vxlan_mdb_remote_srcs_replace().\n\n  BUG: KASAN: slab-use-after-free in __vxlan_mdb_add+0x1cd/0xd70\n  Read of size 8 at addr ffff888102852500 by task poc/84\n   __vxlan_mdb_add+0x1cd/0xd70\n   vxlan_mdb_add+0xc0/0x140\n   rtnl_mdb_add+0x157/0x2a0\n   rtnetlink_rcv_msg+0x207/0x5a0\n  Allocated by task 84:\n   __kmalloc_cache_noprof+0x153/0x360\n   vxlan_mdb_remote_srcs_add+0x2eb/0x440\n   __vxlan_mdb_add+0x803/0xd70\n  Freed by task 84:\n   kfree+0x14c/0x3b0\n   vxlan_mdb_remote_del+0x129/0x1a0\n   __vxlan_mdb_del+0x4f/0xe0\n   vxlan_mdb_remote_src_fwd_del.isra.0+0x162/0x1b0\n   __vxlan_mdb_add+0x1c5/0xd70\n\nThe MDB operations are netns-scoped, so an unprivileged user can perform\nthem in a new user and network namespace.\n\nReject the all-zeros address in vxlan_mdb_is_valid_source(), which covers\nboth call sites. A (*, G) entry is expressed by omitting the source, so\nnothing legitimate is refused.\n\nDiscovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98122","source_modified_at":"2026-10-19T09:14:14.316Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"a3a48de5eade770e911d35291217bdd69ce04ef1","lessThan":"069d5527bb0f229e528fa88c6b72f15060c373f2","status":"affected","versionType":"git"},{"version":"a3a48de5eade770e911d35291217bdd69ce04ef1","lessThan":"e12c903fd13c6261b98ca18d8f70ac26e739e2f8","status":"affected","versionType":"git"},{"version":"a3a48de5eade770e911d35291217bdd69ce04ef1","lessThan":"74e2a56c82209b0335b53e25f19f9b0590e2483d","status":"affected","versionType":"git"},{"version":"a3a48de5eade770e911d35291217bdd69ce04ef1","lessThan":"71203a41d6fa2fa0ea2f3a7541987958bd3694fd","status":"affected","versionType":"git"},{"version":"a3a48de5eade770e911d35291217bdd69ce04ef1","lessThan":"4aa61c88b4e292e10abdfd791334b8272108d68a","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98122","source_modified_at":"2026-10-19T09:14:14.316Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"6.4","status":"affected"},{"version":"0","lessThan":"6.4","status":"unaffected","versionType":"semver"},{"version":"6.6.158","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.111","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.7","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98122","source_modified_at":"2026-10-19T09:14:14.316Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"069d5527bb0f229e528fa88c6b72f15060c373f2","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98122","source_modified_at":"2026-10-19T09:14:14.316Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"74e2a56c82209b0335b53e25f19f9b0590e2483d","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98122","source_modified_at":"2026-10-19T09:14:14.316Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"71203a41d6fa2fa0ea2f3a7541987958bd3694fd","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98122","source_modified_at":"2026-10-19T09:14:14.316Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"4aa61c88b4e292e10abdfd791334b8272108d68a","basis":"first unaffected version stated in the CVE record"}],"cvss":7.8,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00125,"percentile":0.02012,"score_date":"2026-10-23"},"published_at":"2026-09-25T10:36:05.369Z","modified_at":"2026-10-19T09:14:14.316Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98122","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T09:14:14.316Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98122","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/069d5527bb0f229e528fa88c6b72f15060c373f2"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/e12c903fd13c6261b98ca18d8f70ac26e739e2f8"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/74e2a56c82209b0335b53e25f19f9b0590e2483d"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/71203a41d6fa2fa0ea2f3a7541987958bd3694fd"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/4aa61c88b4e292e10abdfd791334b8272108d68a"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T09:14:14.316Z","content_hash":"1758c93ffd2b3dbb08ee94bd9d2c356ac9de110141df24dff60a592a19b9ffe6"}}