# CVE-2026-99108: ntfs: fix FITRIM range alignment


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-99108, GHSA-8qcr-mmv6-jjc8, UBUNTU-CVE-2026-99108

## What is CVE-2026-99108?

CVE-2026-99108 is a vulnerability in Linux, published on 28 Oct 2026. 

### Official description

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

ntfs: fix FITRIM range alignment

ntfs_trim_fs() aligns the start of a free extent up to the device discard
granularity, but derives the discard length by aligning the original extent
length down. When the free extent start is not discard-aligned, adding that
length to the aligned start can extend the discard past the free extent and
into allocated clusters.

For example, with 4 KiB clusters and 32 KiB discard granularity, the free
extent [4 KiB, 36 KiB) becomes the discard range [32 KiB, 64 KiB), so
28 KiB beyond the free extent may be discarded.

Align the absolute end of the free extent down and derive the length from
the two aligned endpoints. Skip extents that contain no full discard unit.

Reproduced with a 4 KiB-cluster NTFS filesystem on scsi_debug configured
for 32 KiB discard granularity and read-zero-after-trim. Before this
change, FITRIM zeroed seven allocated 4 KiB clusters following an unaligned
32 KiB hole. With this change, the same data remains intact across FITRIM
and remount.

## Which versions are affected by CVE-2026-99108?


## How do I fix CVE-2026-99108?

Upgrade to a fixed version.

## Is CVE-2026-99108 being exploited?

There is no known exploitation of CVE-2026-99108 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99108 and fix it if it is affected.

What it is: CVE-2026-99108 is a vulnerability in Linux, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99108 in the wild and no public exploit code.

Affected product: Linux. 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-2026-99108/ (Markdown: https://insights.sbomify.com/CVE-2026-99108/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99108
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99108
- OSV: https://osv.dev/vulnerability/CVE-2026-99108

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99108/
Summaries are generated and may contain mistakes; the official description above is the record.