Heap out-of-bounds write via unchecked delta writes
Published Aug 20, 2026 · Updated Aug 20, 2026
Heap out-of-bounds write in GraphicsMagick before 1.3.48 allows attackers to corrupt heap memory via a crafted PCD file. In DecodeImage() in coders/pcd.c, the Huffman delta loop increments q after each decoded delta and writes into heap-allocated luma or chroma plane buffers without checking whether q has passed the allocation boundary between sync markers. Reachability requires a PCD file to be processed by gm convert, gm identify, or an application linked against libGraphicsMagick; the published record confirms heap corruption but does not document impact beyond the parser process.
Summary
What happened
Heap out-of-bounds write in GraphicsMagick before 1.3.48 allows attackers to corrupt heap memory via a crafted PCD file. In DecodeImage() in coders/pcd.c, the Huffman delta loop increments q after each decoded delta and writes into heap-allocated luma or chroma plane buffers without checking whether q has passed the allocation boundary between sync markers. Reachability requires a PCD file to be processed by gm convert, gm identify, or an application linked against libGraphicsMagick; the published record confirms heap corruption but does not document impact beyond the parser process.
The record
- CVE
- CVE-2026-77118
- Published
- Aug 20, 2026
- Updated
- Aug 20, 2026
- Vendor
- GraphicsMagick Group
- Product
- GraphicsMagick
- Classifications
- CWE-787
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 20, 2026CVE publishedPublication date reported by the CVE source.
- Aug 20, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.3.48
- Affected versionversion=0 <1.4+really1.3.48-1
- Affected versionversion=1.0.0 <1.3.48
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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