CVE-2026-59941

Dompdf is an HTML to PDF converter for PHP. Versions 3.15 and prior accept a BMP image and generates a PDF-compatible PNG based only on its declared header dimensions and never bounds width × height before the image is converted through GD. A 58-byte BMP whose header declares e.g. 6000×6000 is accepted and later drives imagecreatetruecolor($width, $height) (and PHP's native BMP decoder) to allocate the full pixel canvas. A payload can fit in a single HTTP request: the BMP can be inlined as a data:image/bmp;base64,… URI inside attacker-controlled HTML, so no upload, no remote fetch, and no chroot-reachable file is required. I measured a 169-byte request driving a dompdf render to ~412 MB peak RSS and ~4.8 s of CPU/wall time, versus ~34 MB for an identically-sized benign request — roughly a 12× memory amplification per request, repeatable and unauthenticated. This issue has been fixed in version 3.16.

• CWE-400

• https://github.com/dompdf/dompdf/commit/7c65e7bbeccf146b2409740405af73949ad129d0Patch
• https://github.com/dompdf/dompdf/releases/tag/v3.1.6Release Notes
• https://github.com/dompdf/dompdf/security/advisories/GHSA-8hg6-c449-896mExploit, Vendor Advisory
• https://github.com/dompdf/dompdf/security/advisories/GHSA-8hg6-c449-896mExploit, Vendor Advisory

Published

Jul 28, 2026

Last Modified

Aug 4, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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