{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89688","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.749Z","datePublished":"2026-09-11T19:46:09.322Z","dateUpdated":"2026-09-13T06:33:12.290Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-13T06:33:12.290Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: drop the stateid, not the stateowner, on seqid_op replay retry\n\nIn nfs4_preprocess_seqid_op() the stateid is obtained from\nnfsd4_lookup_stateid(), which holds a reference on the nfs4_stid\n(sc_count) but takes no reference on the stateowner. openlockstateid()\nmerely casts that stid and likewise takes no reference.\n\nWhen nfsd4_cstate_assign_replay() returns -EAGAIN (the replay owner is\nbeing torn down, RP_UNHASHED) it has not taken a stateowner reference on\nthat path. The error handling nevertheless called\nnfs4_put_stateowner(stp->st_stateowner), dropping an so_count reference\nthe function never acquired -- risking a stateowner refcount underflow and\nuse-after-free -- while leaking the sc_count reference held on the stid.\nThe leaked stid reference can also stall a concurrent\nnfsd4_close_open_stateid() waiting for sc_count to drop.\n\nDrop the reference actually held -- the stid -- before retrying. The\nstateowner stays alive through the reference held by the stid. This mirrors\nthe open path in nfsd4_process_open1(), where the put balances a reference\nthat path explicitly holds on the stateowner."}],"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 - nfsd processes NFSv4 COMPOUND ops (CLOSE, OPEN_DOWNGRADE, LOCK, OPEN_CONFIRM) in the in-kernel NFS server on TCP/UDP 2049; those handlers call nfs4_preprocess_seqid_op(), so a remote peer reaches the bug with no local access.\nAC:L - A remote NFSv4.0 client drives both sides by sending concurrent CLOSE and another seqid-mutating op on the same openowner; CLOSE's move_to_close_lru() sets RP_UNHASHED and waits on sc_count, so the window is attacker-controlled and retryable.\nPR:N - Typical nfsd exports use AUTH_SYS/AUTH_NULL, so RPC uids are self-asserted and not cryptographically verified; any host allowed by the export list can SETCLIENTID, OPEN, then CLOSE/OPEN_DOWNGRADE with no local Linux account.\nUI:N - The attacker issues the NFSv4 COMPOUND requests itself; no victim on the server must mount a filesystem, open a file, or take any other action.\nS:U - The underflow frees an nfsd nfs4_stateowner in the NFS server kernel; impact stays in that kernel and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - nfs4_put_stateowner() drops an so_count the seqid path never took, freeing the stateowner while the stid and retry loop still use it; that UAF enables slab reclaim and kernel memory disclosure.\nI:H - The same UAF exposes so_ops->so_unhash/so_free function pointers and list writes under cl_lock, yielding a kernel write and control-flow hijack primitive.\nA:H - The UAF oopses or panics nfsd; the leaked stid sc_count also leaves move_to_close_lru() waiting forever for sc_count==2, hanging an nfsd thread, and the -EAGAIN retry can spin while RP_UNHASHED stays set."}]}],"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":"eec7620800081e27dbf8019ac2e66259f0d5bf6f","lessThan":"69ed78b6b947c9257213164678b4edf17533093b","status":"affected","versionType":"git"},{"version":"eec7620800081e27dbf8019ac2e66259f0d5bf6f","lessThan":"00843074d9b84824552c9679d423d29500ca5de0","status":"affected","versionType":"git"},{"version":"eec7620800081e27dbf8019ac2e66259f0d5bf6f","lessThan":"f7cb90ddc021747fc9abfd4cf5252d425fd34eec","status":"affected","versionType":"git"},{"version":"eec7620800081e27dbf8019ac2e66259f0d5bf6f","lessThan":"5e4627d3513e60accfce9d5f4c7fa95251ef93d6","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":"6.10","status":"affected"},{"version":"0","lessThan":"6.10","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-rc1","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":"6.10","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/69ed78b6b947c9257213164678b4edf17533093b"},{"url":"https://git.kernel.org/stable/c/00843074d9b84824552c9679d423d29500ca5de0"},{"url":"https://git.kernel.org/stable/c/f7cb90ddc021747fc9abfd4cf5252d425fd34eec"},{"url":"https://git.kernel.org/stable/c/5e4627d3513e60accfce9d5f4c7fa95251ef93d6"}],"title":"nfsd: drop the stateid, not the stateowner, on seqid_op replay retry","x_generator":{"engine":"bippy-1.2.0"}}}}