nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget The XDR buffer size calculation in nfsd4_ff_encode_layoutget() has multiple errors that can result in either an out-of-bounds write or leaking uninitialized kernel memory to the client: - fh_len doesn't account for XDR padding on the file handle data - uid and gid lengths use "8 + len" but xdr_encode_opaque() actually writes "4 + xdr_align_size(len)" bytes - ds_len omits the flags and stats_collect_hint fields (8 bytes), while len's header constant overestimates by 8 bytes -- these partially cancel but leave a net mismatch The worst case occurs with short strings (e.g. uid=0, gid=0 with an odd-sized file handle), where the function writes up to 5 bytes past the reserved XDR buffer. Conversely, when string lengths happen to be 4-byte aligned, the reservation is too large and stale buffer content is sent to the client. Fix this by breaking out every encoded field explicitly in the ds_len calculation, using xdr_align_size() for all variable-length opaque fields, and correcting the header constants.
CVE-2026-89674
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-2026-89674
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": "9b9960a0ca4773e21c4b153ed355583946346b25",
"lessThan": "3a7fd224df0fbb42167eb1b77be45d72fe0b1098",
"versionType": "git"
},
{
"status": "affected",
"version": "9b9960a0ca4773e21c4b153ed355583946346b25",
"lessThan": "29e4478e2ed5a227e8f0c33cacb91bf227cedd47",
"versionType": "git"
},
{
"status": "affected",
"version": "9b9960a0ca4773e21c4b153ed355583946346b25",
"lessThan": "65a72b721943618eeb3a41c8b36e915591f3f83f",
"versionType": "git"
},
{
"status": "affected",
"version": "9b9960a0ca4773e21c4b153ed355583946346b25",
"lessThan": "bee826c00ac900473f91306f1f3e5a5a81fd4a74",
"versionType": "git"
},
{
"status": "affected",
"version": "9b9960a0ca4773e21c4b153ed355583946346b25",
"lessThan": "e7d9d23ecd9172f05b09bb678ff22db8e361c428",
"versionType": "git"
},
{
"status": "affected",
"version": "9b9960a0ca4773e21c4b153ed355583946346b25",
"lessThan": "0380129b1373c437eb35401a174671c8888f4b80",
"versionType": "git"
},
{
"status": "affected",
"version": "9b9960a0ca4773e21c4b153ed355583946346b25",
"lessThan": "c81cef6a805dec266c10fc4f83c93d6fcf1a2b43",
"versionType": "git"
},
{
"status": "affected",
"version": "9b9960a0ca4773e21c4b153ed355583946346b25",
"lessThan": "f9868174af49d207fbaf0c5e055d088a983684af",
"versionType": "git"
}
],
"programFiles": [
"fs/nfsd/flexfilelayoutxdr.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.8"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.8",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"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/flexfilelayoutxdr.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89674
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #35164 · Revision 1
- Added to Heist Feed
- Publisher date