# CVE-2026-98125: smb/client: fix stale page cache in insert/collapse range

> A local attacker can read stale data from the page cache after SMB insert/collapse range operations due to improper cache invalidation.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-104277, BELL-CVE-2026-98125, DEBIAN-CVE-2026-98125, GHSA-mgrf-j38j-q2mg, UBUNTU-CVE-2026-98125

## What is CVE-2026-98125?

CVE-2026-98125 is a medium-severity vulnerability in Linux kernel, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-669 (Incorrect Resource Transfer Between Spheres)

## Which versions are affected by CVE-2026-98125?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-98125?

Apply the vendor's patch.

## Is CVE-2026-98125 being exploited?

There is no known exploitation of CVE-2026-98125 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98125 and fix it if it is affected.

What it is: CVE-2026-98125 is a medium-severity vulnerability in Linux kernel, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98125 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98125/ (Markdown: https://insights.sbomify.com/CVE-2026-98125/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98125
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98125
- OSV: https://osv.dev/vulnerability/CVE-2026-98125

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98125/
Summaries are generated and may contain mistakes; the official description above is the record.