High · CVSS 7.5CVE-2026-106117

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

Answer in brief

CVE-2026-106117 records a High severity (CVSS 7.5) vulnerability in ImageSharp: CCITT fax decompression (T4/Modified Huffman): unbounded WriteBits overflows strip buffer — heap OOB write in SixLabors.ImageSharp. The current sources do not mark it as known exploited. The current feed maps SixLabors/ImageSharp (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 6, 2026Updated Oct 6, 2026Source checked Oct 6, 2026First seen by HOL Oct 6, 2026Material review Oct 6, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps SixLabors/ImageSharp (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
SixLabors/ImageSharpgeneric	>=3.0.0 <4.1.1	4.1.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for SixLabors/ImageSharp.
Review the reported fix. Update SixLabors/ImageSharp to 4.1.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Oct 6, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 6, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 6, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.