{"api_version":"1","generated_at":"2026-10-27T04:27:44+00:00","cve":"CVE-2026-98487","urls":{"html":"https://cve.report/CVE-2026-98487","api":"https://cve.report/api/cve/CVE-2026-98487.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98487","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98487"},"summary":{"title":"net: bridge: mdb: restart port group walk after deletion","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mdb: restart port group walk after deletion\n\nbr_mdb_flush_pgs() keeps a pointer-to-pointer cursor while walking\nmp->ports. br_multicast_del_pg() can re-enter the same MDB entry through\nbr_multicast_sg_del_exclude_ports() and unlink other port groups. If the\ncursor points into one of those groups, the next iteration dereferences a\nstale cursor and can leave mp->ports pointing at freed memory.\n\nA following RTM_GETMDB exposes the dangling pointer:\n\n  BUG: KASAN: slab-use-after-free in br_mdb_dump\n  Read of size 8\n    br_mdb_dump\n    rtnl_mdb_dump\n    rtnl_dumpit\n    netlink_dump\n\nReset the cursor to mp->ports after every deletion. The deletion removes at\nleast the selected group, so the restarted walk always makes progress.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-18 16:16:59","updated_at":"2026-10-24 14:16:43"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/ab3c4a4c85f2e1e8d04b5c1770dea8412d21c7fe","name":"https://git.kernel.org/stable/c/ab3c4a4c85f2e1e8d04b5c1770dea8412d21c7fe","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ab1404ac81154a89fb61ac50ae9a04cd8d4834dc","name":"https://git.kernel.org/stable/c/ab1404ac81154a89fb61ac50ae9a04cd8d4834dc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fe2a42789c12eb7c5d3a42191e2cc735a6c35ead","name":"https://git.kernel.org/stable/c/fe2a42789c12eb7c5d3a42191e2cc735a6c35ead","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/46ec55855c972504258c371677ac039ba20e5d12","name":"https://git.kernel.org/stable/c/46ec55855c972504258c371677ac039ba20e5d12","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98487","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98487","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a6acb535afb2a3b688a7858f05b61f0433e480d5 46ec55855c972504258c371677ac039ba20e5d12 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a6acb535afb2a3b688a7858f05b61f0433e480d5 ab3c4a4c85f2e1e8d04b5c1770dea8412d21c7fe git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a6acb535afb2a3b688a7858f05b61f0433e480d5 fe2a42789c12eb7c5d3a42191e2cc735a6c35ead git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a6acb535afb2a3b688a7858f05b61f0433e480d5 ab1404ac81154a89fb61ac50ae9a04cd8d4834dc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.8","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.8 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.112 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.55 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.9 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/bridge/br_mdb.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"46ec55855c972504258c371677ac039ba20e5d12","status":"affected","version":"a6acb535afb2a3b688a7858f05b61f0433e480d5","versionType":"git"},{"lessThan":"ab3c4a4c85f2e1e8d04b5c1770dea8412d21c7fe","status":"affected","version":"a6acb535afb2a3b688a7858f05b61f0433e480d5","versionType":"git"},{"lessThan":"fe2a42789c12eb7c5d3a42191e2cc735a6c35ead","status":"affected","version":"a6acb535afb2a3b688a7858f05b61f0433e480d5","versionType":"git"},{"lessThan":"ab1404ac81154a89fb61ac50ae9a04cd8d4834dc","status":"affected","version":"a6acb535afb2a3b688a7858f05b61f0433e480d5","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/bridge/br_mdb.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.8"},{"lessThan":"6.8","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.112","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.55","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.9","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.112","versionStartIncluding":"6.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.55","versionStartIncluding":"6.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.9","versionStartIncluding":"6.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"6.8","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mdb: restart port group walk after deletion\n\nbr_mdb_flush_pgs() keeps a pointer-to-pointer cursor while walking\nmp->ports. br_multicast_del_pg() can re-enter the same MDB entry through\nbr_multicast_sg_del_exclude_ports() and unlink other port groups. If the\ncursor points into one of those groups, the next iteration dereferences a\nstale cursor and can leave mp->ports pointing at freed memory.\n\nA following RTM_GETMDB exposes the dangling pointer:\n\n  BUG: KASAN: slab-use-after-free in br_mdb_dump\n  Read of size 8\n    br_mdb_dump\n    rtnl_mdb_dump\n    rtnl_dumpit\n    netlink_dump\n\nReset the cursor to mp->ports after every deletion. The deletion removes at\nleast the selected group, so the restarted walk always makes progress."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - A local sendmsg() on NETLINK_ROUTE carrying RTM_DELMDB with NLM_F_BULK reaches the patched br_mdb_flush_pgs() through rtnl_mdb_del() and ndo_mdb_del_bulk; received bridge packets do not enter this bulk-delete path.\nAC:L - The attacker can add a *,G EXCLUDE membership and permanent static S,G groups so br_multicast_sg_add_exclude_ports() creates skipped kernel-protocol STAR_EXCL nodes; a proto-static bulk flush then deterministically invalidates pp without a race.\nPR:L - rtnetlink_rcv_msg() requires CAP_NET_ADMIN through netlink_net_capable(), but an unprivileged user can obtain that capability in a user-created network namespace and create the bridge, ports, and MDB state there.\nUI:N - The attacker performs the RTM_NEWMDB setup, NLM_F_BULK RTM_DELMDB trigger, and optional RTM_GETMDB traversal through their own netlink socket; no victim action is required.\nS:U - The dangling mp->ports pointer corrupts and exposes bridge objects within the host kernel's existing security authority; it does not cross a guest-host, hypervisor, or IOMMU boundary.\nC:H - The persistent slab UAF lets reclaimed contents control p->next and p->key.port; br_mdb_fill_info() follows these links and returns port, timer, flag, and source-list data through RTM_GETMDB, enabling kernel-memory disclosure.\nI:H - Reusing the dangling node in br_multicast_del_pg() reaches hlist_del_init_rcu() through reclaimed pg->mglist.pprev and updates rhashtable and GC links, providing attacker-influenced kernel writes and potential control-flow hijacking.\nA:H - After br_multicast_destroy_port_group() calls kfree_rcu(), br_mdb_dump() produces the confirmed slab-use-after-free; stale p->key.port or p->next dereferences in dump or br_multicast_flood can oops or panic the kernel."}]}],"providerMetadata":{"dateUpdated":"2026-10-24T14:09:03.998Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/46ec55855c972504258c371677ac039ba20e5d12"},{"url":"https://git.kernel.org/stable/c/ab3c4a4c85f2e1e8d04b5c1770dea8412d21c7fe"},{"url":"https://git.kernel.org/stable/c/fe2a42789c12eb7c5d3a42191e2cc735a6c35ead"},{"url":"https://git.kernel.org/stable/c/ab1404ac81154a89fb61ac50ae9a04cd8d4834dc"}],"title":"net: bridge: mdb: restart port group walk after deletion","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98487","datePublished":"2026-10-18T15:16:04.746Z","dateReserved":"2026-09-25T10:25:14.352Z","dateUpdated":"2026-10-24T14:09:03.998Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-18 16:16:59","lastModifiedDate":"2026-10-24 14:16:43","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98487","Ordinal":"1","Title":"net: bridge: mdb: restart port group walk after deletion","CVE":"CVE-2026-98487","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98487","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mdb: restart port group walk after deletion\n\nbr_mdb_flush_pgs() keeps a pointer-to-pointer cursor while walking\nmp->ports. br_multicast_del_pg() can re-enter the same MDB entry through\nbr_multicast_sg_del_exclude_ports() and unlink other port groups. If the\ncursor points into one of those groups, the next iteration dereferences a\nstale cursor and can leave mp->ports pointing at freed memory.\n\nA following RTM_GETMDB exposes the dangling pointer:\n\n  BUG: KASAN: slab-use-after-free in br_mdb_dump\n  Read of size 8\n    br_mdb_dump\n    rtnl_mdb_dump\n    rtnl_dumpit\n    netlink_dump\n\nReset the cursor to mp->ports after every deletion. The deletion removes at\nleast the selected group, so the restarted walk always makes progress.","Type":"Description","Title":"net: bridge: mdb: restart port group walk after deletion"}]}}}