ImageSharp: TIFF CCITT T4 encoder can write past its compressed output buffer

[ Why it matters ]Priority signals

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

[ Description ]Official description

ImageSharp is a 2D graphics library. From 2.0.0 until 4.1.2, the TIFF CCITT Group 3 encoder allocates an undersized compressed-data buffer for narrow 1-bit images. TiffCcittCompressor.Initialize does not reserve enough space for the row data and T4 end-of-line codes, and T4BitCompressor.CompressStrip reaches unchecked writes when TiffCompression.CcittGroup3Fax is selected directly or inherited from decoded TIFF metadata. An attacker-controlled encode or decode-and-re-encode flow can write beyond the logical output span, corrupt process memory, and terminate the process. This issue is fixed in version 4.1.2.

[ Fixes ]Fixes and patches

• SixLabors.ImageSharp 4.1.2Fixed version · GitHub Advisories · nuget package SixLabors.ImageSharp: upgrade to 4.1.2 or later (affected >= 2.0.0, <= 4.1.1)

[ Packages ]Affected open-source packages

• SixLabors.ImageSharp nugetAffected >= 2.0.0, <= 4.1.1 · fixed in 4.1.2 · GHSA-j9gm-c75j-xc9q

[ References ]References

• github.com/SixLabors/ImageSharp/commit/a9498c6db3642ef92c712ebc81e706914ac16a95
• github.com/SixLabors/ImageSharp/pull/3187
• github.com/SixLabors/ImageSharp/releases/tag/v4.1.2
• github.com/SixLabors/ImageSharp/security/advisories/GHSA-j9gm-c75j-xc9q