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[ CVE-2026-106117 · Published 6 Oct 2026 ]

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

CVSS 7.5 EPSS <1%Fix available

[ Why it matters ]Priority signals

  • Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]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.

[ Fixes ]Fixes and patches

  • ImageSharp 3.2.0Fixed version · GitHub Advisories · nuget package ImageSharp: upgrade to 3.2.0 or later (affected >= 3.0.0, < 3.2.0)
  • ImageSharp 4.1.1Fixed version · GitHub Advisories · nuget package ImageSharp: upgrade to 4.1.1 or later (affected >= 4.0.0, < 4.1.1)

[ Packages ]Affected open-source packages

[ References ]References