CVE-2026-42146: CImg Library: Uncontrolled memory allocation via nb_colors field in _load_bmp

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-04 · updated 2026-10-26
Weakness: CWE-789

Description

CImg Library is a C++ library for image processing. Prior to commit c3aacf5, the nb_colors field read from the BMP file header is used directly to compute an allocation size without validating it against the remaining file size. A crafted BMP file with a large nb_colors value triggers an out-of-memory condition, crashing any application that uses CImg to load untrusted BMP files. This issue has been patched via commit c3aacf5.

Affected products

GreycLab CImg: before c3aacf5b96ac1e54b7af1957c6737dbf3949f6d3

References

https://github.com/GreycLab/CImg/commit/c3aacf5b96ac1e54b7af1957c6737dbf3949f6d3
https://github.com/GreycLab/CImg/issues/477
https://github.com/GreycLab/CImg/releases/tag/v.3.7.5
https://github.com/GreycLab/CImg/security/advisories/GHSA-g54r-qmgx-c6fv
https://github.com/GreycLab/CImg/issues/477

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