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CVE-2026-77118— Out-of-bounds write in GraphicsMagick PCD decoder

Quick assessment

Affected
GraphicsMagick Group GraphicsMagick
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

GraphicsMagick 的 Photo CD（PCD）解码器中存在堆越界写入漏洞。在 DecodeImage() 函数（位于 coders/pcd.c）中，Huffman 解码循环在每次解码完一个 delta 后通过执行 q++ 来递增输出指针，但从未检查该指针是否超出堆分配的亮度/色度平面缓冲区的边界。指针仅在出现同步标记（sync marker）并引入新的平面或行时才会重新定位；而在两个同步标记之间，运行长度仅由输入数据决定，缺乏有效边界控制。 恶意构造的 PCD 文件可将指针置于接近平面末尾的位置，然后

CVSS 8.4 · High EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 3

VendorProduct Version RangeStatus
Debian graphicsmagick < 1.4+really1.3.48-1 affected
Fedora Project GraphicsMagick < 1.3.48 affected
GraphicsMagick Group GraphicsMagick 1.0.0< 1.3.48 affected
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I. Basic Information for CVE-2026-77118

Vulnerability Information
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Vulnerability Title
Out-of-bounds write in GraphicsMagick PCD decoder
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
GraphicsMagick Group GraphicsMagick 1.0.0 ~ 1.3.48 cpe:2.3:a:graphicsmagick:graphicsmagick:*:*:*:*:*:*:*:*
Debian graphicsmagick 0 ~ 1.4+really1.3.48-1 cpe:2.3:o:debian:debian_linux:11:*:*:*:*:*:*:*
Fedora Project GraphicsMagick 0 ~ 1.3.48 cpe:2.3:a:fedoraproject:extra_packages_for_enterprise_linux:8.0:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-77118

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III. Intelligence Information for CVE-2026-77118

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Patches & Fixes for CVE-2026-77118 (1)

News Coverage for CVE-2026-77118 (1)

IV. Related Vulnerabilities

Same product: GraphicsMagick
Same weakness: CWE-787

V. Comments for CVE-2026-77118

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