{"api_version":"1","generated_at":"2026-09-25T12:40:15+00:00","cve":"CVE-2026-98023","urls":{"html":"https://cve.report/CVE-2026-98023","api":"https://cve.report/api/cve/CVE-2026-98023.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98023","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98023"},"summary":{"title":"vxlan: reject dynamic fdb entries that reference a nexthop id","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: reject dynamic fdb entries that reference a nexthop id\n\nThe commit cited in the Fixes tag allowed VXLAN FDB entries to point to\nFDB nexthops so that overlay traffic could be load balanced across\nmultiple VTEPs. Such entries can only be configured from user space,\ncannot be learned and cannot roam. They only make sense with a user space\ncontrol plane such as E-VPN where data plane learning is disabled.\n\nDespite that, the VXLAN driver does not currently prevent such entries\nfrom being configured with the \"dynamic\" flag. The per-nexthop FDB list\nis only protected by the per-device hash lock, which is not sufficient\nwhen two VXLAN devices point to the same FDB nexthop and therefore share\nthe list. Aging runs in softirq context without RTNL, so an entry deleted\nby one device can race with an addition or deletion from the other,\nleading to list corruption:\n\n  list_del corruption. next->prev should be ffff8881069d9548, but was\n  dead000000000122. (next=ffff8881069d9448)\n  WARNING: CPU: 0 PID: 90 at lib/list_debug.c:65\n  __list_del_entry_valid_or_report+0x1aa/0x210\n  ...\n   vxlan_fdb_destroy+0x5b8/0xad0\n   vxlan_cleanup+0x328/0x450\n   call_timer_fn+0x2a/0x1c0\n   run_timer_softirq+0x18c/0x210\n  BUG: KASAN: slab-use-after-free in vxlan_fdb_destroy\n\nFix this by rejecting the bogus configuration of dynamic FDB entries that\npoint to FDB nexthops, both when created and when an existing entry is\nupdated. As such, the per-nexthop FDB list is only ever mutated under the\nRTNL lock. Add test cases to make sure that this does not regress in the\nfuture.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-25 11:17:30","updated_at":"2026-09-25 11:17:30"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/98fc57d167446b95b4e719815fe79edef93f8e7a","name":"https://git.kernel.org/stable/c/98fc57d167446b95b4e719815fe79edef93f8e7a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/28f86eec851b7406a4bc6143f82aeba2882d9842","name":"https://git.kernel.org/stable/c/28f86eec851b7406a4bc6143f82aeba2882d9842","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/53359916ceb649b7e6947c8c2f669368a41c1354","name":"https://git.kernel.org/stable/c/53359916ceb649b7e6947c8c2f669368a41c1354","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3fa64d86fc64eda104e3e97721a12a42a2fd2073","name":"https://git.kernel.org/stable/c/3fa64d86fc64eda104e3e97721a12a42a2fd2073","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98023","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98023","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1274e1cc42264d4e629841e4f182795cb0becfd2 28f86eec851b7406a4bc6143f82aeba2882d9842 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1274e1cc42264d4e629841e4f182795cb0becfd2 53359916ceb649b7e6947c8c2f669368a41c1354 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1274e1cc42264d4e629841e4f182795cb0becfd2 3fa64d86fc64eda104e3e97721a12a42a2fd2073 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1274e1cc42264d4e629841e4f182795cb0becfd2 98fc57d167446b95b4e719815fe79edef93f8e7a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.8","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.8 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.111 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.53 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.7 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc3 * 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":["drivers/net/vxlan/vxlan_core.c","tools/testing/selftests/net/fib_nexthops.sh"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"28f86eec851b7406a4bc6143f82aeba2882d9842","status":"affected","version":"1274e1cc42264d4e629841e4f182795cb0becfd2","versionType":"git"},{"lessThan":"53359916ceb649b7e6947c8c2f669368a41c1354","status":"affected","version":"1274e1cc42264d4e629841e4f182795cb0becfd2","versionType":"git"},{"lessThan":"3fa64d86fc64eda104e3e97721a12a42a2fd2073","status":"affected","version":"1274e1cc42264d4e629841e4f182795cb0becfd2","versionType":"git"},{"lessThan":"98fc57d167446b95b4e719815fe79edef93f8e7a","status":"affected","version":"1274e1cc42264d4e629841e4f182795cb0becfd2","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/net/vxlan/vxlan_core.c","tools/testing/selftests/net/fib_nexthops.sh"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.8"},{"lessThan":"5.8","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.111","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.53","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.7","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.111","versionStartIncluding":"5.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.53","versionStartIncluding":"5.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.7","versionStartIncluding":"5.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc3","versionStartIncluding":"5.8","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: reject dynamic fdb entries that reference a nexthop id\n\nThe commit cited in the Fixes tag allowed VXLAN FDB entries to point to\nFDB nexthops so that overlay traffic could be load balanced across\nmultiple VTEPs. Such entries can only be configured from user space,\ncannot be learned and cannot roam. They only make sense with a user space\ncontrol plane such as E-VPN where data plane learning is disabled.\n\nDespite that, the VXLAN driver does not currently prevent such entries\nfrom being configured with the \"dynamic\" flag. The per-nexthop FDB list\nis only protected by the per-device hash lock, which is not sufficient\nwhen two VXLAN devices point to the same FDB nexthop and therefore share\nthe list. Aging runs in softirq context without RTNL, so an entry deleted\nby one device can race with an addition or deletion from the other,\nleading to list corruption:\n\n  list_del corruption. next->prev should be ffff8881069d9548, but was\n  dead000000000122. (next=ffff8881069d9448)\n  WARNING: CPU: 0 PID: 90 at lib/list_debug.c:65\n  __list_del_entry_valid_or_report+0x1aa/0x210\n  ...\n   vxlan_fdb_destroy+0x5b8/0xad0\n   vxlan_cleanup+0x328/0x450\n   call_timer_fn+0x2a/0x1c0\n   run_timer_softirq+0x18c/0x210\n  BUG: KASAN: slab-use-after-free in vxlan_fdb_destroy\n\nFix this by rejecting the bogus configuration of dynamic FDB entries that\npoint to FDB nexthops, both when created and when an existing entry is\nupdated. As such, the per-nexthop FDB list is only ever mutated under the\nRTNL lock. Add test cases to make sure that this does not regress in the\nfuture."}],"providerMetadata":{"dateUpdated":"2026-09-25T10:23:42.706Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/28f86eec851b7406a4bc6143f82aeba2882d9842"},{"url":"https://git.kernel.org/stable/c/53359916ceb649b7e6947c8c2f669368a41c1354"},{"url":"https://git.kernel.org/stable/c/3fa64d86fc64eda104e3e97721a12a42a2fd2073"},{"url":"https://git.kernel.org/stable/c/98fc57d167446b95b4e719815fe79edef93f8e7a"}],"title":"vxlan: reject dynamic fdb entries that reference a nexthop id","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98023","datePublished":"2026-09-25T10:23:42.706Z","dateReserved":"2026-09-25T10:19:56.069Z","dateUpdated":"2026-09-25T10:23:42.706Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-25 11:17:30","lastModifiedDate":"2026-09-25 11:17:30","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98023","Ordinal":"1","Title":"vxlan: reject dynamic fdb entries that reference a nexthop id","CVE":"CVE-2026-98023","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98023","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: reject dynamic fdb entries that reference a nexthop id\n\nThe commit cited in the Fixes tag allowed VXLAN FDB entries to point to\nFDB nexthops so that overlay traffic could be load balanced across\nmultiple VTEPs. Such entries can only be configured from user space,\ncannot be learned and cannot roam. They only make sense with a user space\ncontrol plane such as E-VPN where data plane learning is disabled.\n\nDespite that, the VXLAN driver does not currently prevent such entries\nfrom being configured with the \"dynamic\" flag. The per-nexthop FDB list\nis only protected by the per-device hash lock, which is not sufficient\nwhen two VXLAN devices point to the same FDB nexthop and therefore share\nthe list. Aging runs in softirq context without RTNL, so an entry deleted\nby one device can race with an addition or deletion from the other,\nleading to list corruption:\n\n  list_del corruption. next->prev should be ffff8881069d9548, but was\n  dead000000000122. (next=ffff8881069d9448)\n  WARNING: CPU: 0 PID: 90 at lib/list_debug.c:65\n  __list_del_entry_valid_or_report+0x1aa/0x210\n  ...\n   vxlan_fdb_destroy+0x5b8/0xad0\n   vxlan_cleanup+0x328/0x450\n   call_timer_fn+0x2a/0x1c0\n   run_timer_softirq+0x18c/0x210\n  BUG: KASAN: slab-use-after-free in vxlan_fdb_destroy\n\nFix this by rejecting the bogus configuration of dynamic FDB entries that\npoint to FDB nexthops, both when created and when an existing entry is\nupdated. As such, the per-nexthop FDB list is only ever mutated under the\nRTNL lock. Add test cases to make sure that this does not regress in the\nfuture.","Type":"Description","Title":"vxlan: reject dynamic fdb entries that reference a nexthop id"}]}}}