CVE-2026-77118: Debian Graphicsmagick

High severity, CVSS 8.4. EPSS: 0.2% chance of exploitation in the next 30 days.

A heap out-of-bounds write exists in the Photo CD (PCD) decoder of GraphicsMagick. In DecodeImage() (coders/pcd.c), the Huffman delta loop advances its output pointer with q++ after every decoded delta and never checks it against the end of the heap-allocated luma/chroma plane buffers. The pointer is repositioned only when a sync marker introduces a new plane/row; between sync markers the run length is bounded solely by the input. A crafted PCD file that positions the pointer near the end of a plane and then supplies a long run of deltas with no intervening sync therefore walks the pointer past the end of the allocation and writes through it. Processing an untrusted PCD file — for example with gm convert or gm identify, or through any application linked against libGraphicsMagick — can corrupt heap memory beyond the buffers.

Affected products

• Debian Graphicsmagick: before 1.4+really1.3.48-1 (fixed in 1.4+really1.3.48-1)
• Fedora Project Graphicsmagick: before 1.3.48 (fixed in 1.3.48)
• Graphicsmagick Group Graphicsmagick: from 1.0.0, before 1.3.48 (fixed in 1.3.48)

Published 2026-08-20. Last modified 2026-09-09.