{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21795", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.767Z", "datePublished": "2025-02-27T02:18:31.538Z", "dateUpdated": "2026-08-05T11:54:30.327Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:54:30.327Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: fix hang in nfsd4_shutdown_callback\n\nIf nfs4_client is in courtesy state then there is no point to send\nthe callback. This causes nfsd4_shutdown_callback to hang since\ncl_cb_inflight is not 0. This hang lasts about 15 minutes until TCP\nnotifies NFSD that the connection was dropped.\n\nThis patch modifies nfsd4_run_cb_work to skip the RPC call if\nnfs4_client is in courtesy state." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable code is in the in-kernel NFS server (nfsd) and is reached entirely through NFSv4 protocol operations (OPEN/delegation, LOCK) from a remote network client over the wire.\nAC:L - The attacker controls both sides — obtaining a delegation then dropping its connection to become a courtesy client, and issuing the conflicting operation that forces the recall — and the recall itself deterministically triggers the expiry that hangs on the in-flight SOFTCONN RPC, so the ~15-minute hang is reliably reproducible.\nPR:N - NFS exports commonly use AUTH_SYS (no real authentication) and may be accessible to a subnet or anonymously, so an unauthenticated network client can perform the OPEN/delegation and conflicting-lock operations needed; no verified privilege is required.\nUI:N - The attacker's own NFS operations set up and trigger the hang; no action by any legitimate user or administrator is needed.\nS:U - The hang is confined to the NFS server's own kernel context and workqueues; it does not cross a security/authority boundary such as a VM or IOMMU boundary.\nC:N - The defect is a wait/hang on an in-flight callback with no memory disclosure or out-of-bounds read; no confidential information is exposed.\nI:N - No data is modified or corrupted; the bug only stalls the callback-shutdown path and involves no write primitive or state alteration.\nA:H - `nfsd4_shutdown_callback` hangs for ~15 minutes, blocking the laundromat workqueue (all lease/state/delegation/lock cleanup) and lock-conflict resolution that flushes the same queue, and the stall can be triggered repeatedly — a severe denial of 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/nfs4callback.c" ], "versions": [ { "version": "67ef9e5fd737eab2495f2586df7e9ea30caa1b77", "lessThan": "abed68027ea3ab893ac85cc46a00e2e64a324239", "status": "affected", "versionType": "git" }, { "version": "26540b8940a2e21582afa61a6fb8af87310bac72", "lessThan": "efa8a261c575f816c7e79a87aeb3ef8a0bd6b221", "status": "affected", "versionType": "git" }, { "version": "66af25799940b26efd41ea6e648f75c41a48a2c2", "lessThan": "38d345f612503b850c2973e5a879f88e441b34d7", "status": "affected", "versionType": "git" }, { "version": "66af25799940b26efd41ea6e648f75c41a48a2c2", "lessThan": "23ad7797c74cd8f7f90617f1e59a8703e2b43908", "status": "affected", "versionType": "git" }, { "version": "66af25799940b26efd41ea6e648f75c41a48a2c2", "lessThan": "cedfbb92cf97a6bff3d25633001d9c44442ee854", "status": "affected", "versionType": "git" }, { "version": "66af25799940b26efd41ea6e648f75c41a48a2c2", "lessThan": "e88d2451cd42e025465d6b51fd716a47b0b3800d", "status": "affected", "versionType": "git" }, { "version": "66af25799940b26efd41ea6e648f75c41a48a2c2", "lessThan": "036ac2778f7b28885814c6fbc07e156ad1624d03", "status": "affected", "versionType": "git" }, { "version": "5.10.220", "lessThan": "5.10.235", "status": "affected", "versionType": "semver" }, { "version": "5.15.154", "lessThan": "5.15.179", "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/nfs4callback.c" ], "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.235", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.179", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.129", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.79", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.16", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13.4", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14", "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": "5.10.235" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.154", "versionEndExcluding": "5.15.179" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.1.129" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.6.79" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.16" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.13.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.14" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/abed68027ea3ab893ac85cc46a00e2e64a324239" }, { "url": "https://git.kernel.org/stable/c/efa8a261c575f816c7e79a87aeb3ef8a0bd6b221" }, { "url": "https://git.kernel.org/stable/c/38d345f612503b850c2973e5a879f88e441b34d7" }, { "url": "https://git.kernel.org/stable/c/23ad7797c74cd8f7f90617f1e59a8703e2b43908" }, { "url": "https://git.kernel.org/stable/c/cedfbb92cf97a6bff3d25633001d9c44442ee854" }, { "url": "https://git.kernel.org/stable/c/e88d2451cd42e025465d6b51fd716a47b0b3800d" }, { "url": "https://git.kernel.org/stable/c/036ac2778f7b28885814c6fbc07e156ad1624d03" } ], "title": "NFSD: fix hang in nfsd4_shutdown_callback", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:59:38.867Z" } }, { "x_adpType": 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