---
id: CVE-2026-89665
title: 'nfsd: reject out-of-range useconds in NFSv2 SETATTR/CREATE'
summary: "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: reject out-of-range useconds in NFSv2 SETATTR/CREATE\n\nThe NFSv2 sattr decoder converts the wire useconds to nanoseconds in\nsvcxdr_decode_sattr():\n\n\tiap->ia_atime.…"
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L'
cvssSource: cna
cwe:
  - CWE-190
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    cdc3299f7072777b09c9582a3b8b65bb163ddcf3
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    09a79d9ab35a39603c834e8f6333603292f9c816
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    5296a2442d12d45d6eea7b4d3ec3ffecc1821cac
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1db456ffc22e045f49f7b9e62415a26b3f33f200
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    a937dd1aa2d92291fe0a1860d17e90d8f206cd22
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    ad02d095439f89cbd6629420c7e3ba476457b83b
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1195483965a5f63d2dde18054ec7e50a23b9071c
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    26709c8ffe73772eb69e68d553ac71d91228dccc
  - Linux 2.6.12
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-16T19:25:40.808424Z'
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:50:36.772Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89665'
references:
  - url: 'https://git.kernel.org/stable/c/cdc3299f7072777b09c9582a3b8b65bb163ddcf3'
  - url: 'https://git.kernel.org/stable/c/09a79d9ab35a39603c834e8f6333603292f9c816'
  - url: 'https://git.kernel.org/stable/c/5296a2442d12d45d6eea7b4d3ec3ffecc1821cac'
  - url: 'https://git.kernel.org/stable/c/1db456ffc22e045f49f7b9e62415a26b3f33f200'
  - url: 'https://git.kernel.org/stable/c/a937dd1aa2d92291fe0a1860d17e90d8f206cd22'
  - url: 'https://git.kernel.org/stable/c/ad02d095439f89cbd6629420c7e3ba476457b83b'
  - url: 'https://git.kernel.org/stable/c/1195483965a5f63d2dde18054ec7e50a23b9071c'
  - url: 'https://git.kernel.org/stable/c/26709c8ffe73772eb69e68d553ac71d91228dccc'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89665.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89665'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532498'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89665'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89665'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89665.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00621
epssPercentile: 0.49548
scores:
  cna: 8.2
  vendor: 7
ingestedAt: '2026-09-14T15:23:07.450Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

nfsd: reject out-of-range useconds in NFSv2 SETATTR/CREATE

The NFSv2 sattr decoder converts the wire useconds to nanoseconds in
svcxdr_decode_sattr():

	iap->ia_atime.tv_nsec = tmp2 * NSEC_PER_USEC;

tmp2 is a u32 and NSEC_PER_USEC is 1000, so the product is computed in
unsigned long. On ILP32 that is 32 bits, and an out-of-range useconds
value such as 4294968 wraps to tv_nsec == 704. The corruption therefore
happens during decode, before any proc function can inspect the value,
and a later range check on tv_nsec would see an in-range result and
accept it. Rejecting in the decoder yields an RPC GARBAGE_ARGS reply.
NFSv2 defines no NFSERR_INVAL, so there is no NFS-level status to return
for a malformed time argument, and the check cannot move to the proc
function the way the v3/v4 nsec range checks do.

Guard the raw useconds before the multiplication and reject values
greater than 1000000. useconds == 1000000 is kept: it is the Sun
convention for "set to the current server time", and the in-tree Linux
NFSv2 client emits it in both the atime and the mtime field for a plain
touch / utimes(file, NULL) (see encode_sattr() and
xdr_encode_current_server_time() in fs/nfs/nfs2xdr.c). Rejecting 1000000
would turn that common operation into a hard decode failure for both
SETATTR and CREATE. 1000000 * NSEC_PER_USEC is 10^9, which does not wrap
on ILP32, so the Sun convention value passes through safely. Only
genuinely out-of-range values (> 1000000) are rejected. The atime and
mtime guards are therefore symmetric.

The decoder only applied the Sun convention in the mtime block, which
clears ATTR_ATIME_SET|ATTR_MTIME_SET when mtime useconds == 1000000. If a
client puts 1000000 in the atime field but not in the mtime field, the
atime block stored an out-of-range tv_nsec (10^9) and left ATTR_ATIME_SET
set, so the bogus value reached the filesystem. Apply the convention in
the atime block as well, clearing ATTR_ATIME_SET so the server uses its
current time and ignores the value. Only ATTR_ATIME_SET is cleared there.
The mtime block keeps its existing behavior, where 1000000 means "set
both atime and mtime to now".

[ cel: various tweaks, addenda, and clean-ups ]

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cdc3299f7072777b09c9582a3b8b65bb163ddcf3`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 09a79d9ab35a39603c834e8f6333603292f9c816`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5296a2442d12d45d6eea7b4d3ec3ffecc1821cac`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1db456ffc22e045f49f7b9e62415a26b3f33f200`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a937dd1aa2d92291fe0a1860d17e90d8f206cd22`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < ad02d095439f89cbd6629420c7e3ba476457b83b`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1195483965a5f63d2dde18054ec7e50a23b9071c`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 26709c8ffe73772eb69e68d553ac71d91228dccc`
- `Linux 2.6.12`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat OpenShift Container Platform 4 · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89665.json)