NFSD: check truncate permission under inode lock
In the Linux kernel, the following vulnerability has been resolved: NFSD: check truncate permission under inode lock nfsd_setattr() checks whether a size update needs NFSD_MAY_TRUNC before it takes inode_lock(). The comparison uses the file size sampled by that unlocked read, but the actual ATTR_SIZE update is applied later under inode_lock() by notify_change(). This leaves a TOCTOU window for append-only files. If a client sends a SETATTR that does not shrink the file at the time of the unlocked sample, a concurrent append can extend the file before nfsd_setattr() takes inode_lock(). notify_change() then applies a real truncation without the NFSD_MAY_TRUNC check that rejects IS_APPEND(inode). The VFS truncate syscall paths perform their own append-only checks before calling notify_change(), so NFSD must make this decision against the locked size it is about to change. Split the write-count acquisition from the truncation permission check. Keep get_write_access() before the locked setattr work, then recheck whether the requested size is below i_size_read(inode) after inode_lock() has been acquired and before notify_change(ATTR_SIZE). This also avoids the plain unlocked inode->i_size load.
CVE-2026-89713
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-89713
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "783112f7401ff449d979530209b3f6c2594fdb4e",
"lessThan": "52d0c5bdfe232c9974d4b11f97078b9c7814f05d",
"versionType": "git"
},
{
"status": "affected",
"version": "783112f7401ff449d979530209b3f6c2594fdb4e",
"lessThan": "3afa17d93ba8c925f49370c816c6dae5112d8c24",
"versionType": "git"
},
{
"status": "affected",
"version": "783112f7401ff449d979530209b3f6c2594fdb4e",
"lessThan": "d8352da196349182e1afd5a93308256cddc0a97d",
"versionType": "git"
},
{
"status": "affected",
"version": "783112f7401ff449d979530209b3f6c2594fdb4e",
"lessThan": "44086254479035de42ca3d286ecf25521d4e6325",
"versionType": "git"
},
{
"status": "affected",
"version": "783112f7401ff449d979530209b3f6c2594fdb4e",
"lessThan": "b778e0e0a16759f22a70579c3cf8d254a40d4a7f",
"versionType": "git"
},
{
"status": "affected",
"version": "604a3c407026d6162d15300478e63f901e435efc",
"versionType": "git"
},
{
"status": "affected",
"version": "cc4d5dc73841b98d33cdfb9822d70b0aac4beca5",
"versionType": "git"
},
{
"status": "affected",
"version": "3ee4f442e5b37a537297b812557b1163f96b5399",
"versionType": "git"
},
{
"status": "affected",
"version": "a3c6cbc4eac4473ed5461d5faae2794d3e5c0e44",
"versionType": "git"
},
{
"status": "affected",
"version": "982898d7f97a35447403c3fcecc0d96c646ce101",
"versionType": "git"
},
{
"status": "affected",
"version": "3.2.89",
"lessThan": "3.3",
"versionType": "semver"
},
{
"status": "affected",
"version": "3.16.44",
"lessThan": "3.17",
"versionType": "semver"
},
{
"status": "affected",
"version": "4.4.53",
"lessThan": "4.5",
"versionType": "semver"
},
{
"status": "affected",
"version": "4.9.14",
"lessThan": "4.10",
"versionType": "semver"
},
{
"status": "affected",
"version": "4.10.2",
"lessThan": "4.11",
"versionType": "semver"
}
],
"programFiles": [
"fs/nfsd/vfs.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.11"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.11",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/nfsd/vfs.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89713
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #46712 · Revision 1
- Added to Heist Feed
- Publisher date