{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89682", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.748Z", "datePublished": "2026-09-11T19:46:04.882Z", "dateUpdated": "2026-10-21T12:48:18.923Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:48:18.923Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net\n\nnfsd_file_dispose_list_delayed() defers fput() to nfsd service threads\nvia a per-net freeme queue, preventing the shrinker and GC worker from\nbearing the cost of closing files (see ffb402596147). However, the\nqueue lives in a separately-allocated struct nfsd_fcache_disposal that\nis freed by nfsd_free_fcache_disposal_net() during per-net teardown.\nThe global shrinker, laundrette, and fsnotify callbacks can still be\ninside nfsd_file_dispose_list_delayed() dereferencing that pointer,\ncausing a use-after-free.\n\nInline the spinlock and freeme list directly into struct nfsd_net (as\nfcache_dispose_lock and fcache_dispose_list), eliminating the separately\nallocated struct nfsd_fcache_disposal entirely. These fields now have\nthe same lifetime as the net namespace itself, so there is no dangling\npointer to chase.\n\nnfsd_file_cache_start_net() now just initializes the inline fields and\ncannot fail due to allocation. nfsd_file_cache_shutdown_net() drains\nthe inline list directly instead of freeing a separate struct. The\nalloc/free helpers are removed." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - nfsd_file_dispose_list_delayed() runs in the in-kernel NFS server filecache on nfsd_files cached from remote OPEN/READ/WRITE over TCP/UDP 2049; a network NFS client populates that cache and can drive delayed dispose via the global GC laundrette, shrinker, or fsnotify from REMOVE, matching kernel guidance that nfsd is Network.\nAC:H - The UAF requires nfsd_free_fcache_disposal_net() to kfree the separately allocated per-net nfsd_fcache_disposal during nfsd_file_cache_shutdown_net() while the global shrinker, laundrette, or fsnotify still dereference it—a victim-side nfsd restart, shutdown, or netns teardown the remote attacker cannot cause, only race against.\nPR:N - Typical nfsd deployments use AUTH_SYS/AUTH_NULL with IP-based exports, so a remote peer that can reach the export self-asserts credentials with no cryptographic authentication and can OPEN/READ files into the filecache; no local Linux account or capability is required.\nUI:N - The attacker issues NFS operations that populate and reclaim the filecache themselves; nfsd per-net teardown is an environmental race counted under Attack Complexity, not an interactive victim action such as mounting a filesystem or opening a file.\nS:U - The use-after-free corrupts host-kernel slab (struct nfsd_fcache_disposal) within the same OS security authority as nfsd and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - This is a slab use-after-free of the kmalloc'd nfsd_fcache_disposal object; reclaim or spray of the freed object lets dispose_list_delayed read attacker-controlled lock and list_head fields, enabling arbitrary kernel disclosure per UAF guidance.\nI:H - spin_lock and list_move_tail on the freed disposal object write into reclaimed slab, corrupting list nodes and lock state and yielding a groomable write or control-flow hijack primitive characteristic of exploitable kernel UAFs.\nA:H - Use-after-free of the disposal spinlock and list from shrinker, GC worker, or fsnotify context causes kernel oops, panic, or list-corruption hangs, 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/filecache.c", "fs/nfsd/netns.h" ], "versions": [ { "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408", "lessThan": "e6c3a43d0a41f03abae3764fc82a59369360c7e0", "status": "affected", "versionType": "git" }, { "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408", "lessThan": "9c8ac7c2b9b150e13b7ad0d0fae54f17747dce67", "status": "affected", "versionType": "git" }, { "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408", "lessThan": "ba0ee9e04b7a0356c28d5a2fe445db675d24e572", "status": "affected", "versionType": "git" }, { "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408", "lessThan": "cadc9036d5a8209f89e7026ddba7cfb1c716b03c", "status": "affected", "versionType": "git" }, { "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408", "lessThan": "bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4", "status": "affected", "versionType": "git" }, { "version": "e8f923e1e9fcc0832a12c8a2461792e5a9544c03", "status": "affected", "versionType": "git" }, { "version": "3bc94fb44f10ef852723e1aeaac6794c5ab16aec", "status": "affected", "versionType": "git" }, { "version": "5.10.220", "lessThan": "5.11", "status": "affected", "versionType": "semver" }, { "version": "5.15.154", "lessThan": "5.16", "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/filecache.c", "fs/nfsd/netns.h" ], "versions": [ { "version": "5.17", "status": "affected" }, { "version": "0", "lessThan": "5.17", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.114", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.51", "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": "5.17", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.12.114" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.18.51" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "7.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.220" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.154" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/e6c3a43d0a41f03abae3764fc82a59369360c7e0" }, { "url": "https://git.kernel.org/stable/c/9c8ac7c2b9b150e13b7ad0d0fae54f17747dce67" }, { "url": "https://git.kernel.org/stable/c/ba0ee9e04b7a0356c28d5a2fe445db675d24e572" }, { "url": "https://git.kernel.org/stable/c/cadc9036d5a8209f89e7026ddba7cfb1c716b03c" }, { "url": "https://git.kernel.org/stable/c/bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4" } ], "title": "nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net", "x_generator": { "engine": "bippy-1.2.0" } } } }