CVE-2026-89712

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89712", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.751Z", "datePublished": "2026-09-11T19:46:27.018Z", "dateUpdated": "2026-10-19T08:51:25.202Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:51:25.202Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock\n\nnfsd4_ssc_expire_umount() walks nn->nfsd_ssc_mount_list with\nlist_for_each_entry_safe(ni, tmp, ...). For each expired entry it\nsets nsui_busy = true, drops nfsd_ssc_lock to run mntput() on the\nsource vfsmount, then reacquires the lock to list_del + kfree the\nentry and continue iterating via the macro's saved tmp pointer.\n\nThe nsui_busy flag protects the current ni from concurrent\nnfsd4_ssc_setup_dul() finders during the lock-drop window, but it\ndoes not pin tmp. Another nfsd RPC thread that fails its source-\nserver mount and reaches nfsd4_ssc_cancel_dul() will, during that\nsame window, take nfsd_ssc_lock, list_del + kfree its own ssc_umount\nitem, and release the lock. If that item is the saved tmp of the\nexpire walk, the next iteration dereferences a freed\nnfsd4_ssc_umount_item.\n\nRestart the walk from the head after the mntput() unlock window so\nno saved next pointer survives the lock-drop. The list is bounded\nby the number of active inter-server source mounts (typically small)\nand the expire delayed-work runs periodically rather than per-IO,\nso the restart is cheap."}], "metrics": [{"cvssV3_1": {"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"}, "scenarios": [{"lang": "en", "value": "AV:N - The UAF is between nfsd4_ssc_expire_umount() and nfsd4_ssc_cancel_dul(); cancel_dul runs from nfsd4_copy() on NFSv4.2 OP_COPY, reached by a COMPOUND over TCP/2049 to in-kernel nfsd. A remote client populates nfsd_ssc_mount_list and frees the saved iterator with no local access.\nAC:L - The attacker drives both race sides with concurrent async inter-server COPY requests: completed copies leave expired nfsd4_ssc_umount_item entries for the laundromat, while a COPY to another source IP fails vfs_kern_mount() into cancel_dul() during mntput(). An attacker-controlled source NFS server can stall unmount, so the window is attacker-created and retryable.\nPR:N - Under AUTH_SYS (default for typical NFS deployments) the server verifies no secret; EXCHANGE_ID, CREATE_SESSION, and OPEN succeed for any host allowed by the export, so no server-verified privileges are required to issue the COPY compounds that hit setup_dul/cancel_dul.\nUI:N - The attacker\u2019s own NFS client issues the COPY compounds and source-server traffic that create, expire, and cancel ssc_umount items; no administrator or other user action on the victim server is required.\nS:U - The use-after-free is of a kmalloc\u2019d nfsd4_ssc_umount_item in the nfsd host kernel; impact stays within the same kernel security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - After cancel_dul() kfree()s the saved tmp, the expire walk continues from a freed nfsd4_ssc_umount_item whose vfsmount, list links, and metadata the attacker can replace via slab reuse, giving a UAF read primitive over kernel heap.\nI:H - The expire path then writes nsui_busy, calls mntput() on attacker-controlled nsui_vfsmount, and runs list_del()/kfree() on poisoned pointers, yielding arbitrary-write and control-flow hijack primitives from the same UAF.\nA:H - Dereferencing the freed list node in nfsd4_ssc_expire_umount() oopses or panics the laundromat worker even without a full exploit, taking down the in-kernel NFS server."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/nfsd/nfs4state.c"], "versions": [{"version": "a4bc287943f5695209ff36bdc89f17b48d68fae7", "lessThan": "2b59029b8f24a99b5d844af2da3950d39d36eeea", "status": "affected", "versionType": "git"}, {"version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "lessThan": "d9e151fea5ed706c1284adacabd869b0be745db2", "status": "affected", "versionType": "git"}, {"version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "lessThan": "659ee3da073164e1e6e40dfcbc26eeed85845f93", "status": "affected", "versionType": "git"}, {"version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "lessThan": "60680ae7243b22de3d09be990d8e23bcfc4af837", "status": "affected", "versionType": "git"}, {"version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "lessThan": "77de363d9a1c8cd35f20482782c612cda085791a", "status": "affected", "versionType": "git"}, {"version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "lessThan": "4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8", "status": "affected", "versionType": "git"}, {"version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "lessThan": "7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9", "status": "affected", "versionType": "git"}, {"version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "lessThan": "036c1b182f4da65363e79ec0ac276edc6b7296e5", "status": "affected", "versionType": "git"}, {"version": "5.10.220", "lessThan": "5.10.270", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/nfsd/nfs4state.c"], "versions": [{"version": "5.14", "status": "affected"}, {"version": "0", "lessThan": "5.14", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.220", "versionEndExcluding": "5.10.270"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "5.15.221"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.1.188"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.6.157"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.12.109"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2b59029b8f24a99b5d844af2da3950d39d36eeea"}, {"url": "https://git.kernel.org/stable/c/d9e151fea5ed706c1284adacabd869b0be745db2"}, {"url": "https://git.kernel.org/stable/c/659ee3da073164e1e6e40dfcbc26eeed85845f93"}, {"url": "https://git.kernel.org/stable/c/60680ae7243b22de3d09be990d8e23bcfc4af837"}, {"url": "https://git.kernel.org/stable/c/77de363d9a1c8cd35f20482782c612cda085791a"}, {"url": "https://git.kernel.org/stable/c/4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8"}, {"url": "https://git.kernel.org/stable/c/7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9"}, {"url": "https://git.kernel.org/stable/c/036c1b182f4da65363e79ec0ac276edc6b7296e5"}], "title": "NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/nfsd/nfs4state.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "2b59029b8f24a99b5d844af2da3950d39d36eeea", "status": "affected", "version": "a4bc287943f5695209ff36bdc89f17b48d68fae7", "versionType": "git"}, {"lessThan": "d9e151fea5ed706c1284adacabd869b0be745db2", "status": "affected", "version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "versionType": "git"}, {"lessThan": "659ee3da073164e1e6e40dfcbc26eeed85845f93", "status": "affected", "version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "versionType": "git"}, {"lessThan": "60680ae7243b22de3d09be990d8e23bcfc4af837", "status": "affected", "version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "versionType": "git"}, {"lessThan": "77de363d9a1c8cd35f20482782c612cda085791a", "status": "affected", "version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "versionType": "git"}, {"lessThan": "4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8", "status": "affected", "version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "versionType": "git"}, {"lessThan": "7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9", "status": "affected", "version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "versionType": "git"}, {"lessThan": "036c1b182f4da65363e79ec0ac276edc6b7296e5", "status": "affected", "version": "f4e44b393389c77958f7c58bf4415032b4cda15b", "versionType": "git"}, {"lessThan": "5.10.270", "status": "affected", "version": "5.10.220", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/nfsd/nfs4state.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.14"}, {"lessThan": "5.14", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.270", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.221", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.188", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.157", "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", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock\n\nnfsd4_ssc_expire_umount() walks nn->nfsd_ssc_mount_list with\nlist_for_each_entry_safe(ni, tmp, ...). For each expired entry it\nsets nsui_busy = true, drops nfsd_ssc_lock to run mntput() on the\nsource vfsmount, then reacquires the lock to list_del + kfree the\nentry and continue iterating via the macro's saved tmp pointer.\n\nThe nsui_busy flag protects the current ni from concurrent\nnfsd4_ssc_setup_dul() finders during the lock-drop window, but it\ndoes not pin tmp. Another nfsd RPC thread that fails its source-\nserver mount and reaches nfsd4_ssc_cancel_dul() will, during that\nsame window, take nfsd_ssc_lock, list_del + kfree its own ssc_umount\nitem, and release the lock. If that item is the saved tmp of the\nexpire walk, the next iteration dereferences a freed\nnfsd4_ssc_umount_item.\n\nRestart the walk from the head after the mntput() unlock window so\nno saved next pointer survives the lock-drop. The list is bounded\nby the number of active inter-server source mounts (typically small)\nand the expire delayed-work runs periodically rather than per-IO,\nso the restart is cheap."}], "id": "CVE-2026-89712", "lastModified": "2026-10-19T09:18:10.103", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-11T20:19:58.620", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/036c1b182f4da65363e79ec0ac276edc6b7296e5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/2b59029b8f24a99b5d844af2da3950d39d36eeea"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/60680ae7243b22de3d09be990d8e23bcfc4af837"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/659ee3da073164e1e6e40dfcbc26eeed85845f93"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/77de363d9a1c8cd35f20482782c612cda085791a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d9e151fea5ed706c1284adacabd869b0be745db2"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel NFSD: Denial of service via use-after-free", "id": "2532255", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532255"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-825", "details": ["A flaw was found in the Linux kernel's Network File System Daemon (NFSD) component. A race condition exists where, during the processing of unmounted source-server mounts, a thread may temporarily release a lock. During this window, another NFS Remote Procedure Call (RPC) thread can free memory that the first thread subsequently attempts to access. This use-after-free vulnerability could allow a remote attacker to cause a denial of service."], "name": "CVE-2026-89712", "public_date": "2026-09-11T19:46:27Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89712\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89712\nhttps://git.kernel.org/stable/c/036c1b182f4da65363e79ec0ac276edc6b7296e5\nhttps://git.kernel.org/stable/c/4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8\nhttps://git.kernel.org/stable/c/7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9\nhttps://git.kernel.org/stable/c/77de363d9a1c8cd35f20482782c612cda085791a"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f4e44b393389c77958f7c58bf4415032b4cda15b,77de363d9a1c8cd35f20482782c612cda085791a)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f4e44b393389c77958f7c58bf4415032b4cda15b,4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f4e44b393389c77958f7c58bf4415032b4cda15b,7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f4e44b393389c77958f7c58bf4415032b4cda15b,036c1b182f4da65363e79ec0ac276edc6b7296e5)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "a4bc287943f5695209ff36bdc89f17b48d68fae7"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[5.10.220,5.11)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "5.14"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.14)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.12.109,6.12.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.18.50,6.18.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2.4,7.2.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-12T06:30:09.004268+00:00", "updated": "2026-09-15T20:15:14.377578+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}