{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89658", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.743Z", "datePublished": "2026-09-11T19:45:46.857Z", "dateUpdated": "2026-10-19T08:50:29.852Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:50:29.852Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup\n\nnfs40_clean_admin_revoked() takes a stateid reference under\nclp->cl_lock, drops nn->client_lock, and calls\nnfsd4_drop_revoked_stid(), which dereferences the stateid's client\nthrough s->sc_client->cl_lock. The stateid reference does not pin the\nclient, so a teardown racing the dropped lock can free the client\nwhile nfsd4_drop_revoked_stid() is still using it.\n\nThis cleanup runs from the laundromat, so a periodic sweep can race\nforce_expire_client() driven by a write to the clients//ctl file.\n\nSkip a client that is already expiring and otherwise pin it with\ncl_rpc_users under client_lock before dropping the lock, matching\nnfsd4_revoke_states()." } ], "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 in nfsd NFSv4.0 revoked-state cleanup (nfs40_clean_admin_revoked). A remote peer reaches it over TCP/2049 via nfsd_dispatch to nfsd4_proc_compound: SETCLIENTID/SETCLIENTID_CONFIRM (ALLOWED_WITHOUT_FH) call expire_client() while the laundromat still uses the client.\nAC:L - The attacker controls the expire side by retrying SETCLIENTID_CONFIRM around the known lease interval, or by inducing the documented clients//ctl expire of a misbehaving client. Cleanup drops client_lock without pinning cl_rpc_users, so mark_client_expired_locked succeeds; this is not a race outside attacker influence.\nPR:N - OP_SETCLIENTID and OP_SETCLIENTID_CONFIRM are ALLOWED_WITHOUT_FH/ALLOWED_ON_ABSENT_FS with no export check. Typical nfsd AUTH_SYS/AUTH_NULL deployments never verify RPC credentials, so any host that can reach TCP/2049 can create NFSv4.0 state and trigger the expire.\nUI:N - The attacker drives the NFS compounds that establish state and expire the client. Administrative revoke or ctl expire is a server operational condition (unexport or response to a misbehaving client), not a required victim user action.\nS:U - The freed object is struct nfs4_client in the NFS server kernel. Impact remains in that kernel security authority; there is no VM, IOMMU, or sandbox boundary crossing.\nC:H - nfsd4_drop_revoked_stid() and nfs4_put_stid() dereference s->sc_client after expire_client() frees the nfs4_client. Reclaim of that slab lets an attacker groom contents and disclose kernel memory. Per kernel guidance a UAF is C:H.\nI:H - nfs4_put_stid() lock-and-idr_remove on the freed client's cl_lock/cl_stateids, concurrent with __destroy_client() list walks, is a slab UAF write primitive usable for heap corruption and control-flow hijacking. Per kernel guidance a UAF is I:H.\nA:H - Use of the freed nfs4_client spinlock, IDR, and lists oopses or panics the nfsd host, fully denying service of the 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": "d688d8585e6bea5e4e37f7497feea93b6b0a469c", "lessThan": "0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519", "status": "affected", "versionType": "git" }, { "version": "d688d8585e6bea5e4e37f7497feea93b6b0a469c", "lessThan": "b413ec5b23e3445dc9c4f273116078e2d4747626", "status": "affected", "versionType": "git" }, { "version": "d688d8585e6bea5e4e37f7497feea93b6b0a469c", "lessThan": "81cf7f1413862f87b078920c838460a6a88aa030", "status": "affected", "versionType": "git" }, { "version": "d688d8585e6bea5e4e37f7497feea93b6b0a469c", "lessThan": "7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55", "status": "affected", "versionType": "git" } ] }, { "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": "6.9", "status": "affected" }, { "version": "0", "lessThan": "6.9", "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": "6.9", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519" }, { "url": "https://git.kernel.org/stable/c/b413ec5b23e3445dc9c4f273116078e2d4747626" }, { "url": "https://git.kernel.org/stable/c/81cf7f1413862f87b078920c838460a6a88aa030" }, { "url": "https://git.kernel.org/stable/c/7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55" } ], "title": "NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup", "x_generator": { "engine": "bippy-1.2.0" } } } }