{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89663", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.744Z", "datePublished": "2026-09-11T19:45:50.577Z", "dateUpdated": "2026-10-19T08:50:34.792Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:50:34.792Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: revoke copy-notify stateids before dropping their reference\n\nCopy-notify stateids live in the s2s_cp_stateids IDR and on their parent\nstid's sc_cp_list, pinned by a single membership reference.\n_free_cpntf_state_locked() only unlinks an entry once its refcount reaches\nzero, so any revoke path that runs while a concurrent\nfind_cpntf_state()/manage_cpntf_state() holder has elevated cs_count drops\nthe reference without unlinking, leaving the entry discoverable with its\nmembership reference already consumed. A second revoke or a laundromat tick\nthen frees it while the reader still holds the pointer -- a\nKASAN-detectable use-after-free at the reader's nfs4_put_cpntf_state().\n\nThis affected all three revoke paths:\n\n - The parent-stid drain (nfs4_free_cpntf_statelist()) repeatedly called\n _free_cpntf_state_locked() on the first list entry; a holder that had\n bumped cs_count made it return early, so the next iteration\n re-decremented and burned the holder's reference.\n\n - OFFLOAD_CANCEL (manage_cpntf_state()) and laundromat expiry likewise\n used _free_cpntf_state_locked() and could drop 2->1 without unlinking.\n\nAdd revoke_cpntf_state_locked(), which unhashes the entry from the IDR and\nsc_cp_list first (deferring the final free to any holder), and use it from\nall three revoke paths. The drain now walks with list_for_each_entry_safe()\nand revokes each entry unconditionally, so it terminates in one pass per\nentry regardless of cs_count. The unhash is gated on\n!list_empty(&cps->cp_list); the idr_remove() gate matters because\nidr_alloc_cyclic() may have recycled the so_id by then. Keep\n_free_cpntf_state_locked() for the reference-holder put path only, where a\nconcurrent revoke may already have unlinked the entry (its list_del_init()\nthen a no-op)." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The flaw is in the in-kernel NFS server (nfsd); COPY_NOTIFY, READ using a copy-notify stateid, CLOSE, and OFFLOAD_CANCEL are processed from NFSv4.2 compounds over TCP/2049, so a remote NFS client reaches the use-after-free over the network.\nAC:L - A malicious client fully controls both sides of the race: one compound READs with the copy-notify stateid so find_cpntf_state holds a cs_count reference while a concurrent CLOSE or OFFLOAD_CANCEL drains it; nfs4_free_cpntf_statelist then double-decrements and kfree's the still-linked object with no condition outside attacker control.\nPR:L - The attacker must be an established NFSv4.2 client of an export holding a valid open, lock, or delegation stateid to issue COPY_NOTIFY, which is authenticated low-privilege service access rather than a pre-authentication nfsd path.\nUI:N - No victim action is required; the attacking client drives COPY_NOTIFY, the concurrent READ that holds the cpntf reference, and CLOSE or OFFLOAD_CANCEL on its own NFS connections.\nS:U - The use-after-free corrupts kernel slab memory within the host nfsd security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - Use-after-free of struct nfs4_cpntf_state lets a concurrent find_cpntf_state reader dereference a kfree'd object; heap reuse of that slab gives the attacker control over freed contents, enabling arbitrary kernel memory disclosure.\nI:H - After the drain kfree, the holder still writes cpntf_time and later nfs4_put_cpntf_state runs _free_cpntf_state_locked on the freed object, a use-after-free write primitive usable for controlled memory modification and control-flow hijacking.\nA:H - The KASAN-detectable use-after-free at nfs4_put_cpntf_state oopses or panics nfsd worker threads, fully disrupting availability of the NFS server host." } ] } ], "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": "624322f1adc58acd0b69f77a6ddc764207e97241", "lessThan": "5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d", "status": "affected", "versionType": "git" }, { "version": "624322f1adc58acd0b69f77a6ddc764207e97241", "lessThan": "06a62f6dbc60791f4229c6950b1eec6b18df9af1", "status": "affected", "versionType": "git" }, { "version": "624322f1adc58acd0b69f77a6ddc764207e97241", "lessThan": "a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3", "status": "affected", "versionType": "git" }, { "version": "624322f1adc58acd0b69f77a6ddc764207e97241", "lessThan": "caddbeffab1eaba1d2bcf5ceda35547863466705", "status": "affected", "versionType": "git" }, { "version": "624322f1adc58acd0b69f77a6ddc764207e97241", "lessThan": "6b8149448cdcb476fba4559d1ecc247efee9971b", "status": "affected", "versionType": "git" }, { "version": "624322f1adc58acd0b69f77a6ddc764207e97241", "lessThan": "b56d2c5f01cddbeca7d11cce81d97db4ec9a464f", "status": "affected", "versionType": "git" }, { "version": "624322f1adc58acd0b69f77a6ddc764207e97241", "lessThan": "ff8a3cff02b92b2a82f1a9876038fcf953ae9c25", "status": "affected", "versionType": "git" }, { "version": "624322f1adc58acd0b69f77a6ddc764207e97241", "lessThan": "3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7", "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": "5.6", "status": "affected" }, { "version": "0", "lessThan": "5.6", "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": "5.6", "versionEndExcluding": "5.10.270" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.15.221" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d" }, { "url": "https://git.kernel.org/stable/c/06a62f6dbc60791f4229c6950b1eec6b18df9af1" }, { "url": "https://git.kernel.org/stable/c/a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3" }, { "url": "https://git.kernel.org/stable/c/caddbeffab1eaba1d2bcf5ceda35547863466705" }, { "url": "https://git.kernel.org/stable/c/6b8149448cdcb476fba4559d1ecc247efee9971b" }, { "url": "https://git.kernel.org/stable/c/b56d2c5f01cddbeca7d11cce81d97db4ec9a464f" }, { "url": "https://git.kernel.org/stable/c/ff8a3cff02b92b2a82f1a9876038fcf953ae9c25" }, { "url": "https://git.kernel.org/stable/c/3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7" } ], "title": "nfsd: revoke copy-notify stateids before dropping their reference", "x_generator": { "engine": "bippy-1.2.0" } } } }