Vulnerability · Published May 4, 2026 · Assigned by GitHub_M

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

Medium 5.5

In plain English

A medium-severity security flaw in CImg from GreycLab. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.5Medium

Exploit odds (30 days)0.2%top 92.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	cimg	no fix listed	DEBIAN-CVE-2026-42146
Debian:13	cimg	3.5.2+dfsg-1+deb13u1	DEBIAN-CVE-2026-42146
Debian:14	cimg	3.5.2+dfsg-2	DEBIAN-CVE-2026-42146
Ubuntu:25.10	cimg	no fix listed	UBUNTU-CVE-2026-42146
Ubuntu:26.04:LTS	cimg	no fix listed	UBUNTU-CVE-2026-42146
Ubuntu:26.10	cimg	no fix listed	UBUNTU-CVE-2026-42146

Affected products (as reported)

Vendor	Product	Versions
GreycLab	CImg	< c3aacf5b96ac1e54b7af1957c6737dbf3949f6d3

Weakness: CWE-789 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

References

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