CVE-2026-77118

published 2026-08-20

CVE-2026-77118: 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…

Priority P3 38 high 8.4 CVSS 4.0

AV L AC L AT N PR N UI A VC H VI H VA H SC N SI N SA N E X CR X IR X AR X MAV X MAC X MAT X MPR X MUI X MVC X MVI X MVA X MSC X MSI X MSA X S X AU X R X V X RE X U X

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

3 ranges

Vendor	Product	Version range	Fixed in
debian	graphicsmagick	< 1.4+really1.3.48-1	1.4+really1.3.48-1
fedora_project	graphicsmagick	< 1.3.48	1.3.48
graphicsmagick_group	graphicsmagick	>= 1.0.0 < 1.3.48	1.3.48

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CWE-787