CVE-2026-98125

smb/client: fix stale page cache in insert/collapse range

Published Sep 25, 2026 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

smb/client: fix stale page cache in insert/collapse range

smb3_insert_range() and smb3_collapse_range() use
truncate_pagecache_range() to invalidate the affected page cache.
However, if off or old_eof is not page-aligned, the boundary pages are
only partially zeroed and remain uptodate. As a result, the client may
return stale data after a successful insert/collapse range operation.

For example, with 4K pages:

page 0 page 1 page 2
0------4K 4K------8K 8K------12K
^ ^
off=2K old_eof=10K

Page 1 is removed from the page cache, while the boundary pages are
only partially zeroed. After COPYCHUNK moves the data on the server,
these cached pages may still return stale data.

This can be reproduced on a CIFS mount:

bash -c '
FILE=/mnt/scratch/repro

# Use a 6 KiB file so EOF is not page-aligned.
dd if=/dev/urandom of=/tmp/src bs=1K count=6 status=none

# Expected: a 4 KiB hole followed by the original data.
rm -f /tmp/expected
truncate -s 4K /tmp/expected
cat /tmp/src >> /tmp/expected

cp /tmp/src "$FILE"

# Prime the page cache before moving data on the server.
cat "$FILE" > /dev/null

fallocate --insert-range -o 0 -l 4K "$FILE"

if cmp -s /tmp/expected "$FILE"; then
echo "readback: OK"
else
echo "readback: STALE DATA"
fi
'

Fix this by writing back dirty data and discarding the page cache from
the start of the page containing off to EOF before moving data on the
server.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-9019-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9020-1 Linux kernel vulnerabilities
History
Type Values Removed Values Added
Weaknesses CWE-669
CPEs cpe:2.3:o:linux:linux_kernel:6.0:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.0:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.0:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.0:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.0:rc7:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.3:rc1:*:*:*:*:*:*
Type Values Removed Values Added
Weaknesses CWE-457
Type Values Removed Values Added
Weaknesses CWE-524
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low

Type Values Removed Values Added
Weaknesses CWE-457
Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: smb/client: fix stale page cache in insert/collapse range smb3_insert_range() and smb3_collapse_range() use truncate_pagecache_range() to invalidate the affected page cache. However, if off or old_eof is not page-aligned, the boundary pages are only partially zeroed and remain uptodate. As a result, the client may return stale data after a successful insert/collapse range operation. For example, with 4K pages: page 0 page 1 page 2 0------4K 4K------8K 8K------12K ^ ^ off=2K old_eof=10K Page 1 is removed from the page cache, while the boundary pages are only partially zeroed. After COPYCHUNK moves the data on the server, these cached pages may still return stale data. This can be reproduced on a CIFS mount: bash -c ' FILE=/mnt/scratch/repro # Use a 6 KiB file so EOF is not page-aligned. dd if=/dev/urandom of=/tmp/src bs=1K count=6 status=none # Expected: a 4 KiB hole followed by the original data. rm -f /tmp/expected truncate -s 4K /tmp/expected cat /tmp/src >> /tmp/expected cp /tmp/src "$FILE" # Prime the page cache before moving data on the server. cat "$FILE" > /dev/null fallocate --insert-range -o 0 -l 4K "$FILE" if cmp -s /tmp/expected "$FILE"; then echo "readback: OK" else echo "readback: STALE DATA" fi ' Fix this by writing back dirty data and discarding the page cache from the start of the page containing off to EOF before moving data on the server.
Title smb/client: fix stale page cache in insert/collapse range
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 21, 2026, 12:54 PM
Reserved
Sep 25, 2026, 10:25 AM
Status
Analyzed
Published
Sep 25, 2026, 11:17 AM
Modified
Oct 22, 2026, 4:20 PM
Severity
Low
Public date
Sep 25, 2026, 12:00 AM