Vulnerability · Published Aug 20, 2026 · Assigned by seal
CVE-2026-77118Out-of-bounds write in GraphicsMagick PCD decoder
High 8.4
In plain English
A high-severity out-of-bounds write in graphicsmagick from Debian. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | graphicsmagick | no fix listed | DEBIAN-CVE-2026-77118 |
| Debian:13 | graphicsmagick | no fix listed | DEBIAN-CVE-2026-77118 |
| Debian:14 | graphicsmagick | 1.4+really1.3.48-1 | DEBIAN-CVE-2026-77118 |
| Ubuntu:26.04:LTS | graphicsmagick | no fix listed | UBUNTU-CVE-2026-77118 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| GraphicsMagick Group | GraphicsMagick | 1.0.0 – before 1.3.48 |
| Debian | graphicsmagick | 0 – before 1.4+really1.3.48-1 |
| Fedora Project | GraphicsMagick | 0 – before 1.3.48 |
Weakness: CWE-787 · Vector: 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