{"id":"CVE-2026-98122","revision":"98dd96a91b1f497bb1e5cd9530c9ab46","records":[{"revision":"98dd96a91b1f497bb1e5cd9530c9ab46","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98122","aliases":[],"title":"vxlan: mdb: Fix use-after-free in vxlan_mdb_remote_src_del()","description":"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 ","state":0,"publishedAt":"2026-09-25T10:36:05.369+00:00","modifiedAt":"2026-10-19T09:14:14.316+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"drivers/net/vxlan/vxlan_mdb.c\",\n \"tools/testing/selftests/net/test_vxlan_mdb.sh\"\n ],\n \"versions\": [\n {\n \"version\": \"a3a48de5eade770e911d35291217bdd69ce04ef1\",\n \"lessThan\": \"069d5527bb0f229e528fa88c6b72f15060c373f2\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"a3a48de5eade770e911d35291217bdd69ce04ef1\",\n \"lessThan\": \"e12c903fd13c6261b98ca18d8f70ac26e739e2f8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"a3a48de5eade770e911d35291217bdd69ce04ef1\",\n \"lessThan\": \"74e2a56c82209b0335b53e25f19f9b0590e2483d\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"a3a48de5eade770e911d35291217bdd69ce04ef1\",\n \"lessThan\": \"71203a41d6fa2fa0ea2f3a7541987958bd3694fd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"a3a48de5eade770e911d35291217bdd69ce04ef1\",\n \"lessThan\": \"4aa61c88b4e292e10abdfd791334b8272108d68a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"drivers/net/vxlan/vxlan_mdb.c\",\n \"tools/testing/selftests/net/test_vxlan_mdb.sh\"\n ],\n \"versions\": [\n {\n \"version\": \"6.4\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.4\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.158\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.111\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.53\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2.7\",\n \"lessThanOrEqual\": \"7.2.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.3\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/069d5527bb0f229e528fa88c6b72f15060c373f2","https://git.kernel.org/stable/c/e12c903fd13c6261b98ca18d8f70ac26e739e2f8","https://git.kernel.org/stable/c/74e2a56c82209b0335b53e25f19f9b0590e2483d","https://git.kernel.org/stable/c/71203a41d6fa2fa0ea2f3a7541987958bd3694fd","https://git.kernel.org/stable/c/4aa61c88b4e292e10abdfd791334b8272108d68a"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98122","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98122","identifiers":["CVE-2026-98122"]},"retained":false,"historicalAffected":[]}],"coverage":[]}