{"id":"CVE-2026-89663","title":"nfsd: revoke copy-notify stateids before dropping their reference","summary":"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…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-825"],"vendor":"Linux","product":"Linux","affected":["Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < 5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d","Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < 06a62f6dbc60791f4229c6950b1eec6b18df9af1","Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3","Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < caddbeffab1eaba1d2bcf5ceda35547863466705","Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < 6b8149448cdcb476fba4559d1ecc247efee9971b","Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < b56d2c5f01cddbeca7d11cce81d97db4ec9a464f","Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < ff8a3cff02b92b2a82f1a9876038fcf953ae9c25","Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < 3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7","Linux 5.6"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:50:34.792Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89663","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"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89663.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89663"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532231"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89663"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89663"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89663.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00455,"epssPercentile":0.39353,"scores":{"cna":8.8,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.450Z","slug":"CVE-2026-89663","body":"## Overview\n\nIn 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).\n\n## Affected\n\n- `Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < 5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d`\n- `Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < 06a62f6dbc60791f4229c6950b1eec6b18df9af1`\n- `Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3`\n- `Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < caddbeffab1eaba1d2bcf5ceda35547863466705`\n- `Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < 6b8149448cdcb476fba4559d1ecc247efee9971b`\n- `Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < b56d2c5f01cddbeca7d11cce81d97db4ec9a464f`\n- `Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < ff8a3cff02b92b2a82f1a9876038fcf953ae9c25`\n- `Linux >= 624322f1adc58acd0b69f77a6ddc764207e97241 < 3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7`\n- `Linux 5.6`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-27 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89663.json)","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":224639,"id":"CVE-2026-89663","ts":1792401449477,"field":"cvss","old":"7","new":"8.8"},{"seq":208121,"id":"CVE-2026-89663","ts":1789922717174,"field":"cvss","old":"8.8","new":"7"},{"seq":197777,"id":"CVE-2026-89663","ts":1789384318806,"field":"cvss","old":"6.4","new":"8.8"},{"seq":197776,"id":"CVE-2026-89663","ts":1789384318806,"field":"severity","old":"medium","new":"high"},{"seq":183700,"id":"CVE-2026-89663","ts":1789356677009,"field":"cvss","old":"8.8","new":"6.4"},{"seq":183699,"id":"CVE-2026-89663","ts":1789356677009,"field":"severity","old":"high","new":"medium"},{"seq":153522,"id":"CVE-2026-89663","ts":1789285351134,"field":"cvss","old":null,"new":"8.8"},{"seq":153521,"id":"CVE-2026-89663","ts":1789285351134,"field":"severity","old":"none","new":"high"},{"seq":147584,"id":"CVE-2026-89663","ts":1789270211483,"field":"cvss","old":null,"new":"6.4"},{"seq":147583,"id":"CVE-2026-89663","ts":1789270211483,"field":"severity","old":"none","new":"medium"},{"seq":109340,"id":"CVE-2026-89663","ts":1789183731501,"field":"cvss","old":null,"new":"6.4"},{"seq":109339,"id":"CVE-2026-89663","ts":1789183731501,"field":"severity","old":"none","new":"medium"}]}