CVE-2026-89682 (GCVE-0-2026-89682)
Vulnerability from cvelistv5
Published
2026-09-11 19:46
Modified
2026-10-30 12:32
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net
nfsd_file_dispose_list_delayed() defers fput() to nfsd service threads
via a per-net freeme queue, preventing the shrinker and GC worker from
bearing the cost of closing files (see ffb402596147). However, the
queue lives in a separately-allocated struct nfsd_fcache_disposal that
is freed by nfsd_free_fcache_disposal_net() during per-net teardown.
The global shrinker, laundrette, and fsnotify callbacks can still be
inside nfsd_file_dispose_list_delayed() dereferencing that pointer,
causing a use-after-free.
Inline the spinlock and freeme list directly into struct nfsd_net (as
fcache_dispose_lock and fcache_dispose_list), eliminating the separately
allocated struct nfsd_fcache_disposal entirely. These fields now have
the same lifetime as the net namespace itself, so there is no dangling
pointer to chase.
nfsd_file_cache_start_net() now just initializes the inline fields and
cannot fail due to allocation. nfsd_file_cache_shutdown_net() drains
the inline list directly instead of freeing a separate struct. The
alloc/free helpers are removed.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 1463b38e7cf34d4cc60f41daff459ad807b2e408 Version: 1463b38e7cf34d4cc60f41daff459ad807b2e408 Version: 1463b38e7cf34d4cc60f41daff459ad807b2e408 Version: 1463b38e7cf34d4cc60f41daff459ad807b2e408 Version: 1463b38e7cf34d4cc60f41daff459ad807b2e408 Version: 1463b38e7cf34d4cc60f41daff459ad807b2e408 Version: e8f923e1e9fcc0832a12c8a2461792e5a9544c03 Version: 3bc94fb44f10ef852723e1aeaac6794c5ab16aec Version: 5.10.220 ≤ Version: 5.15.154 ≤ |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/nfsd/filecache.c",
"fs/nfsd/netns.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "41fe0e804bbf1110c0aba2ebdfc729efb240d8a6",
"status": "affected",
"version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
"versionType": "git"
},
{
"lessThan": "e6c3a43d0a41f03abae3764fc82a59369360c7e0",
"status": "affected",
"version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
"versionType": "git"
},
{
"lessThan": "9c8ac7c2b9b150e13b7ad0d0fae54f17747dce67",
"status": "affected",
"version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
"versionType": "git"
},
{
"lessThan": "ba0ee9e04b7a0356c28d5a2fe445db675d24e572",
"status": "affected",
"version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
"versionType": "git"
},
{
"lessThan": "cadc9036d5a8209f89e7026ddba7cfb1c716b03c",
"status": "affected",
"version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
"versionType": "git"
},
{
"lessThan": "bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4",
"status": "affected",
"version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
"versionType": "git"
},
{
"status": "affected",
"version": "e8f923e1e9fcc0832a12c8a2461792e5a9544c03",
"versionType": "git"
},
{
"status": "affected",
"version": "3bc94fb44f10ef852723e1aeaac6794c5ab16aec",
"versionType": "git"
},
{
"lessThan": "5.11",
"status": "affected",
"version": "5.10.220",
"versionType": "semver"
},
{
"lessThan": "5.16",
"status": "affected",
"version": "5.15.154",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/nfsd/filecache.c",
"fs/nfsd/netns.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.17"
},
{
"lessThan": "5.17",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.191",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.51",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.191",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.160",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.114",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.51",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.4",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "5.17",
"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",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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": {
"baseScore": 8.1,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"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\u2014a 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\u0027d 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."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-30T12:32:40.915Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/41fe0e804bbf1110c0aba2ebdfc729efb240d8a6"
},
{
"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"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-89682",
"datePublished": "2026-09-11T19:46:04.882Z",
"dateReserved": "2026-09-11T19:38:34.748Z",
"dateUpdated": "2026-10-30T12:32:40.915Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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