CVE-2026-59942: Dompdf: Denial of Service (DoS) via Resource Exhaustion using Oversized Image Bitmaps

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-07-28 · updated 2026-08-04
Weakness: CWE-400

Description

Dompdf is an HTML to PDF converter for PHP. Versions 3.15 and prior are vulnerable to a Denial of Service (DoS) attack via resource exhaustion. An attacker can crash the PHP process by providing a specially crafted HTML document containing a single image with massive dimensions (e.g., 30,000x30,000 pixels). While Dompdf implements internal checks to validate image dimensions, these can be bypassed by using a high-entropy image (such as random noise) encoded in Base64 and wrapped in specific CSS containers. The vulnerability exists because the dimension validation happens early, but the resource allocation for calculating the object's bounding box and internal buffers during the rendering phase does not strictly limit the cumulative CPU time or memory usage for a single object that has passed the initial check. An unauthenticated remote attacker can cause a complete Denial of Service on the web server by submitting a crafted HTML string. This affects any application that allows users to provide HTML content or URLs that are subsequently converted to PDF using Dompdf. This issue has been fixed in version 3.16.

Affected products

dompdf: before 3.1.6 — fixed in 3.1.6
Packagist Dompdf/Dompdf: before 3.1.6; v0.6.0, v0.6.1, v0.6.2, v0.7.0, v0.7.0-beta, v0.7.0-beta2 (+33) — fixed in 3.1.6

How to fix

Upgrade to a fixed version: dompdf 3.1.6; Packagist Dompdf/Dompdf 3.1.6. Check the vendor advisory for mitigations.

References

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