CVE-2026-89697 (GCVE-0-2026-89697)
Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-13 06:33
VLAI
EPSS
VEX
Title
nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()
Summary
In the Linux kernel, the following vulnerability has been resolved:
nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()
The BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare()
can inspect the dentry. This causes nfsd_setattr() to skip
fh_want_write(), so notify_change() runs without a mount write
reference.
Add the missing fh_want_write() call after the early fh_verify().
Severity
9.1 (Critical)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
cc265089ce1b176dde963c74b53593446ee7f99a , < 15ca3b64a69caa6194bed8f98a20ed90a11c11dd
(git)
Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 533964d420d385e11b08dd4c56c66ef5dcccaf08 (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < c4a409b86a92815181a8e9395c6bf1696ad19175 (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 4e475be769aa9f7a2c1ce55a2b8592cfccacddcc (git) Affected: 1cb57d81cf20fe24b9e2e1daf57bfbdc24b77cd8 (git) Affected: 3.18.46 , < 3.19 (semver) |
guessed | |
| Linux | Linux |
Affected:
4.2
Unaffected: 0 , < 4.2 (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/nfsd/nfsproc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"status": "affected",
"version": "cc265089ce1b176dde963c74b53593446ee7f99a",
"versionType": "git"
},
{
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"status": "affected",
"version": "cc265089ce1b176dde963c74b53593446ee7f99a",
"versionType": "git"
},
{
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"status": "affected",
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"versionType": "git"
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{
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"versionType": "git"
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{
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"status": "affected",
"version": "3.18.46",
"versionType": "semver"
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{
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"product": "Linux",
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],
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"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "4.2"
},
{
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"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.12.109",
"versionType": "semver"
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{
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"status": "unaffected",
"version": "6.18.50",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "7.2.4",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
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"vulnerable": true
},
{
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},
{
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}
],
"negate": false,
"operator": "OR"
}
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}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()\n\nThe BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare()\ncan inspect the dentry. This causes nfsd_setattr() to skip\nfh_want_write(), so notify_change() runs without a mount write\nreference.\n\nAdd the missing fh_want_write() call after the early fh_verify()."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.1,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The bug is in nfsd_proc_setattr(), the in-kernel NFSv2 SETATTR handler. A remote client reaches it by sending an NFSv2 SETATTR RPC over TCP/UDP port 2049 with both atime and mtime set, so no local access to the server is required.\nAC:L - Crafting SETATTR with ATTR_ATIME_SET|ATTR_MTIME_SET and equal timestamps deterministically takes the early fh_verify() path so nfsd_setattr() skips fh_want_write(). The attacker fully controls the RPC; no race or uninfluenced memory layout is required.\nPR:N - Default nfsd exports accept AUTH_SYS and AUTH_NULL with no cryptographic authentication, so the client asserts uid/gid. Any host permitted by the export list can issue SETATTR; this matches prior nfsd CNA scoring as PR:N.\nUI:N - The attacking NFS client issues the SETATTR RPC itself. No administrator or end-user action on the server is required.\nS:U - notify_change() without a mount write reference affects only the exported filesystem in the same kernel security authority. No VM, IOMMU, or sandbox boundary is crossed.\nC:N - The defect is a missing mnt_want_write()/sb_start_write() around notify_change() and commit_metadata(). It does not leak kernel memory, pointers, or file contents beyond ordinary authorized NFS access.\nI:H - nfsd_permission\u0027s read-only check does not cover freeze state, so SETATTR including ATTR_SIZE truncate, mode, and ownership updates proceeds on a frozen export and in a remount-ro race, letting a client mutate files and corrupt snapshots when writes should be blocked.\nA:H - Skipping freeze protection lets setattr run during fsfreeze, which can deadlock (inode_lock versus sb_start_write ordering), trigger filesystem withdraw/asserts such as GFS2 adding buffers while frozen, and hang or crash the nfsd thread."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-13T06:33:21.070Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/15ca3b64a69caa6194bed8f98a20ed90a11c11dd"
},
{
"url": "https://git.kernel.org/stable/c/533964d420d385e11b08dd4c56c66ef5dcccaf08"
},
{
"url": "https://git.kernel.org/stable/c/c4a409b86a92815181a8e9395c6bf1696ad19175"
},
{
"url": "https://git.kernel.org/stable/c/4e475be769aa9f7a2c1ce55a2b8592cfccacddcc"
}
],
"title": "nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()",
"x_generator": {
"engine": "bippy-1.2.0"
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}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-89697",
"datePublished": "2026-09-11T19:46:15.772Z",
"dateReserved": "2026-09-11T19:38:34.750Z",
"dateUpdated": "2026-09-13T06:33:21.070Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-89697",
"date": "2026-09-13",
"epss": "0.00603",
"percentile": "0.46984"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-89697\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-09-11T20:19:56.843\",\"lastModified\":\"2026-09-13T07:17:35.480\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()\\n\\nThe BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare()\\ncan inspect the dentry. This causes nfsd_setattr() to skip\\nfh_want_write(), so notify_change() runs without a mount write\\nreference.\\n\\nAdd the missing fh_want_write() call after the early fh_verify().\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/nfsd/nfsproc.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"cc265089ce1b176dde963c74b53593446ee7f99a\",\"lessThan\":\"15ca3b64a69caa6194bed8f98a20ed90a11c11dd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"cc265089ce1b176dde963c74b53593446ee7f99a\",\"lessThan\":\"533964d420d385e11b08dd4c56c66ef5dcccaf08\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"cc265089ce1b176dde963c74b53593446ee7f99a\",\"lessThan\":\"c4a409b86a92815181a8e9395c6bf1696ad19175\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"cc265089ce1b176dde963c74b53593446ee7f99a\",\"lessThan\":\"4e475be769aa9f7a2c1ce55a2b8592cfccacddcc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1cb57d81cf20fe24b9e2e1daf57bfbdc24b77cd8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"3.18.46\",\"lessThan\":\"3.19\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/nfsd/nfsproc.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.2\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.2\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.109\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.50\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H\",\"baseScore\":9.1,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.2}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/15ca3b64a69caa6194bed8f98a20ed90a11c11dd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/4e475be769aa9f7a2c1ce55a2b8592cfccacddcc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/533964d420d385e11b08dd4c56c66ef5dcccaf08\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c4a409b86a92815181a8e9395c6bf1696ad19175\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
"redhat_vex": {
"aggregate_severity": "Important",
"current_release_date": "2026-09-13T06:52:17+00:00",
"cve": "CVE-2026-89697",
"id": "CVE-2026-89697",
"initial_release_date": "2026-09-11T19:46:15.772000+00:00",
"product_status:known_affected": "2",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: Linux kernel: NFS daemon bypasses write verification during attribute setting",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89697.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-12T16:23:31Z",
"cve": "CVE-2026-89697",
"id": "CVE-2026-89697",
"initial_release_date": "2026-09-12T16:23:31Z",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-89697",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89697.json",
"version": "2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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