# CVE-2026-106117: ImageSharp: CCITT fax decompression (T4/Modified Huffman): unbounded WriteBits overflows strip buffer — heap OOB write in SixLabors.ImageSharp

> Attackers can cause heap overflow and potential code execution by crafting malicious TIFF images processed by the ImageSharp library.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 6 Oct 2026
- **Also known as:** ECHO-58f4-65d8-34a6, GHSA-jj3q-cwqj-842r

## What is CVE-2026-106117?

CVE-2026-106117 is a high-severity memory corruption vulnerability in SixLabors ImageSharp, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ImageSharp is a 2D graphics library. From 3.0.0 until 4.1.1, decoding a strip TIFF using CCITT Group 3 or Modified Huffman compression can pass attacker-expanded runs to BitWriterUtils.WriteBits without first checking the current row width. T4TiffCompression.WritePixelRun can accumulate oversized makeup-code runs, and ModifiedHuffmanTiffCompression.Decompress validates the width only after writing. The unchecked writes can overflow the strip buffer, corrupt heap memory, and terminate the process. This strip-path vulnerability is distinct from the tiled decompressor-width mismatch. This issue is fixed in version 4.1.1.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-106117?

4 open source packages ship an affected version, including ImageSharp. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ImageSharp` | NuGet | From 3.0.0 | 3.2.0 |
| `ImageSharp` | NuGet | From 3.0.0 | 3.2.0 |
| `ImageSharp` | NuGet | From 4.0.0 | 4.1.1 |
| `ImageSharp` | NuGet | From 4.0.0 | 4.1.1 |

Products: Sixlabors Imagesharp.

## How do I fix CVE-2026-106117?

Upgrade ImageSharp to a fixed version for your release line: 3.2.0 or 4.1.1.

## Is CVE-2026-106117 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-106117 exists.

## Other vulnerabilities in SixLabors ImageSharp

- [CVE-2026-106110](https://insights.sbomify.com/CVE-2026-106110/): ImageSharp: TIFF CCITT T4 encoder can write past its compressed output buffer (high 7.5)
- [CVE-2026-106112](https://insights.sbomify.com/CVE-2026-106112/): ImageSharp: ICC LUT16 output channel count can write beyond Vector4 (high 7.5)
- [CVE-2026-106113](https://insights.sbomify.com/CVE-2026-106113/): ImageSharp: HistogramEqualization uses an unvalidated luminance as an unchecked histogram index (high 7.5)
- [CVE-2026-106115](https://insights.sbomify.com/CVE-2026-106115/): ImageSharp: TIFF CCITT T6 encoder writes beyond an undersized output buffer (high 7.5)
- [CVE-2025-27598](https://insights.sbomify.com/CVE-2025-27598/): Out-of-bounds Write in SixLabors ImageSharp (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-106117 and fix it if it is affected.

What it is: CVE-2026-106117 is a high-severity memory corruption vulnerability in SixLabors ImageSharp, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-106117 exists.

Affected packages and fixed versions:
- ImageSharp (NuGet): affected from 3.0.0; fixed in 3.2.0
- ImageSharp (NuGet): affected from 3.0.0; fixed in 3.2.0
- ImageSharp (NuGet): affected from 4.0.0; fixed in 4.1.1
- ImageSharp (NuGet): affected from 4.0.0; fixed in 4.1.1

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-2026-106117/ (Markdown: https://insights.sbomify.com/CVE-2026-106117/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-106117
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-106117
- OSV: https://osv.dev/vulnerability/CVE-2026-106117

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-106117/
Summaries are generated and may contain mistakes; the official description above is the record.