{"api_version":"1","generated_at":"2026-10-16T22:07:09+00:00","cve":"CVE-2026-89686","urls":{"html":"https://cve.report/CVE-2026-89686","api":"https://cve.report/api/cve/CVE-2026-89686.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89686","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89686"},"summary":{"title":"nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke\n\nnfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding\nfi_lock when the parent stateid is a delegation. A concurrent delegation\nrevoke via the laundromat can clear fi_deleg_file under fi_lock, causing\nnfsd_file_get() to return NULL and triggering the BUG_ON.\n\nThis race is client-reachable: two NFS clients can trigger it by having\none hold a delegation while another opens the same file to force a\nrecall. When the first client doesn't respond to the recall, the\nlaundromat revokes it. A concurrent LAYOUTGET from any client using the\ndelegation stateid hits the race window.\n\nFix this by taking fi_lock around the fi_deleg_file read in the\nSC_TYPE_DELEG path, matching the locking discipline of the\nfind_any_file() arm, and replacing the BUG_ON with a graceful error\nreturn that cleans up the partially-initialized layout stateid.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:55","updated_at":"2026-10-16 20:18:26"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/607a56fea772c1f4f4989d8e255dd4f7192d9604","name":"https://git.kernel.org/stable/c/607a56fea772c1f4f4989d8e255dd4f7192d9604","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/97bda8b4284d90897a1f1922e5082ff9e35d7c7e","name":"https://git.kernel.org/stable/c/97bda8b4284d90897a1f1922e5082ff9e35d7c7e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ca94ba36172046be6a694a7986f6931e47ed4d51","name":"https://git.kernel.org/stable/c/ca94ba36172046be6a694a7986f6931e47ed4d51","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c517f27498757e616d2a8fe6d16caad1fee422e6","name":"https://git.kernel.org/stable/c/c517f27498757e616d2a8fe6d16caad1fee422e6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89686","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89686","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c5c707f96fc9a6e5a57ca5baac892673270abe3d c517f27498757e616d2a8fe6d16caad1fee422e6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c5c707f96fc9a6e5a57ca5baac892673270abe3d 607a56fea772c1f4f4989d8e255dd4f7192d9604 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c5c707f96fc9a6e5a57ca5baac892673270abe3d 97bda8b4284d90897a1f1922e5082ff9e35d7c7e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c5c707f96fc9a6e5a57ca5baac892673270abe3d ca94ba36172046be6a694a7986f6931e47ed4d51 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"89686","cve":"CVE-2026-89686","epss":"0.006710000","percentile":"0.500730000","score_date":"2026-09-14","updated_at":"2026-09-15 00:00:42"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-89686","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","timestamp":"2026-10-16T19:26:03.140311Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-10-16T19:26:48.827Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/nfsd/nfs4layouts.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"c517f27498757e616d2a8fe6d16caad1fee422e6","status":"affected","version":"c5c707f96fc9a6e5a57ca5baac892673270abe3d","versionType":"git"},{"lessThan":"607a56fea772c1f4f4989d8e255dd4f7192d9604","status":"affected","version":"c5c707f96fc9a6e5a57ca5baac892673270abe3d","versionType":"git"},{"lessThan":"97bda8b4284d90897a1f1922e5082ff9e35d7c7e","status":"affected","version":"c5c707f96fc9a6e5a57ca5baac892673270abe3d","versionType":"git"},{"lessThan":"ca94ba36172046be6a694a7986f6931e47ed4d51","status":"affected","version":"c5c707f96fc9a6e5a57ca5baac892673270abe3d","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/nfsd/nfs4layouts.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.0"},{"lessThan":"4.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","versionStartIncluding":"4.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"4.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"4.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"4.0","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke\n\nnfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding\nfi_lock when the parent stateid is a delegation. A concurrent delegation\nrevoke via the laundromat can clear fi_deleg_file under fi_lock, causing\nnfsd_file_get() to return NULL and triggering the BUG_ON.\n\nThis race is client-reachable: two NFS clients can trigger it by having\none hold a delegation while another opens the same file to force a\nrecall. When the first client doesn't respond to the recall, the\nlaundromat revokes it. A concurrent LAYOUTGET from any client using the\ndelegation stateid hits the race window.\n\nFix this by taking fi_lock around the fi_deleg_file read in the\nSC_TYPE_DELEG path, matching the locking discipline of the\nfind_any_file() arm, and replacing the BUG_ON with a graceful error\nreturn that cleans up the partially-initialized layout stateid."}],"metrics":[{"cvssV3_1":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:N - The flaw is in nfsd pNFS LAYOUTGET (nfsd4_alloc_layout_stateid in fs/nfsd/nfs4layouts.c). A remote NFSv4.1 client reaches it over TCP/2049 via nfsd_dispatch to nfsd4_proc_compound to nfsd4_layoutget, so no local access to the NFS server is required.\nAC:L - The attacker controls both sides of the race: one NFS client obtains a delegation while another OPENs the same file to force recall, then the first client withholds CB_RECALL and issues concurrent LAYOUTGET with the delegation stateid as the laundromat runs put_deleg_file. The sequence is retryable and can be timed using FATTR4_LEASE_TIME.\nPR:N - Typical nfsd deployments accept AUTH_SYS/AUTH_NULL without cryptographic authentication. Any host allowed by the export ACL can EXCHANGE_ID/CREATE_SESSION, OPEN to receive a delegation, and LAYOUTGET; no local account or capability on the NFS server is required.\nUI:N - The attacking NFS clients drive the OPEN, recall, and LAYOUTGET compounds themselves against an already-running nfsd export. No victim user action such as mounting a filesystem or opening a file on the server is required.\nS:U - The unlocked fi_deleg_file load and resulting BUG_ON or nfsd_file use-after-free occur in kernel nfsd state on the NFS server host. Impact stays in that kernel security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - put_deleg_file may drop the last nfsd_file ref and call_rcu-free it (KMEM_CACHE flags 0, not SLAB_TYPESAFE_BY_RCU) while LAYOUTGET still calls nfsd_file_get on the stale pointer. After slab reuse the layout stateid's nf_file can be leveraged for kernel information disclosure.\nI:H - The same stale nfsd_file pointer is used for refcount_inc_not_zero and later nfsd4_layout_setlease/kernel_setlease on nf_file. Heap reuse of the nfsd_file slab enables an arbitrary write or control-flow hijack per kernel UAF scoring guidance.\nA:H - When nfsd_file_get returns NULL the original code hits BUG_ON(!ls->ls_file), oopsing or panicking the nfsd thread. Even without that assertion, use-after-free of nfsd_file crashes nfsd, and the attacker can repeat LAYOUTGET to deny NFS service."}]}],"providerMetadata":{"dateUpdated":"2026-09-13T06:33:09.795Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/c517f27498757e616d2a8fe6d16caad1fee422e6"},{"url":"https://git.kernel.org/stable/c/607a56fea772c1f4f4989d8e255dd4f7192d9604"},{"url":"https://git.kernel.org/stable/c/97bda8b4284d90897a1f1922e5082ff9e35d7c7e"},{"url":"https://git.kernel.org/stable/c/ca94ba36172046be6a694a7986f6931e47ed4d51"}],"title":"nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89686","datePublished":"2026-09-11T19:46:07.877Z","dateReserved":"2026-09-11T19:38:34.749Z","dateUpdated":"2026-10-16T19:26:48.827Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:55","lastModifiedDate":"2026-10-16 20:18:26","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-10-16T19:26:03.140311Z","id":"CVE-2026-89686","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89686","Ordinal":"1","Title":"nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegat","CVE":"CVE-2026-89686","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89686","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke\n\nnfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding\nfi_lock when the parent stateid is a delegation. A concurrent delegation\nrevoke via the laundromat can clear fi_deleg_file under fi_lock, causing\nnfsd_file_get() to return NULL and triggering the BUG_ON.\n\nThis race is client-reachable: two NFS clients can trigger it by having\none hold a delegation while another opens the same file to force a\nrecall. When the first client doesn't respond to the recall, the\nlaundromat revokes it. A concurrent LAYOUTGET from any client using the\ndelegation stateid hits the race window.\n\nFix this by taking fi_lock around the fi_deleg_file read in the\nSC_TYPE_DELEG path, matching the locking discipline of the\nfind_any_file() arm, and replacing the BUG_ON with a graceful error\nreturn that cleans up the partially-initialized layout stateid.","Type":"Description","Title":"nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegat"}]}}}