Dompdf: Denial of Service (DoS) via Resource Exhaustion using Oversized Image Bitmaps

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-59942: 0.90% estimated exploitation activity in the next 30 days; percentile 59.71 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Dompdf v3.1.5 is 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. Technical Deep Dive: Standard solid-color images can often be optimized by compression algorithms or rendering engines. However, a high-entropy noise image forces the PHP engine to process each of the 900 million pixels individually. When render() is called, the engine attempts to handle the uncompressed bitmap in memory and calculate the layout for every high-variance pixel data point. This leads to: - 100% CPU Saturation: The rendering thread hangs indefinitely trying to process the pixel stream. - Process Termination: The…

Published by the source

22 Jul 2026, 22:51 UTC

Last modified by the source

22 Jul 2026, 22:51 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-f5gf-2cj8-52g2

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# Patch Next advisory brief: CVE-2026-59942

Advisory: Dompdf: Denial of Service (DoS) via Resource Exhaustion using Oversized Image Bitmaps
IDs: CVE-2026-59942, GHSA-f5gf-2cj8-52g2
Record: https://patchnext.com/advisories/cve-2026-59942 (revision 1, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: dompdf/dompdf 3.1.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist dompdf/dompdf: affected < 3.1.6; fixed in 3.1.6

## Suggested inspection (read-only)
- Packagist dompdf/dompdf: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on dompdf/dompdf.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f5gf-2cj8-52g2 (GitHub-reviewed advisory GHSA-f5gf-2cj8-52g2 lists affected ranges: Packagist dompdf/dompdf >=0 <3.1.6)

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