CVE-2026-29074: SVGO: DoS through entity expansion in DOCTYPE (Billion Laughs)

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-06 · updated 2026-09-10
Weakness: CWE-776

Description

SVGO, short for SVG Optimizer, is a Node.js library and command-line application for optimizing SVG files. From version 2.1.0 to before version 2.8.1, from version 3.0.0 to before version 3.3.3, and before version 4.0.1, SVGO accepts XML with custom entities, without guards against entity expansion or recursion. This can result in a small XML file (811 bytes) stalling the application and even crashing the Node.js process with JavaScript heap out of memory. This issue has been patched in versions 2.8.1, 3.3.3, and 4.0.1.

Affected products

svgo: from 2.1.0 before 2.8.1; from 3.0.0 before 3.3.3; from 4.0.0 before 4.0.1 — fixed in 2.8.1, 3.3.3, 4.0.1

How to fix

Upgrade to a fixed version: svgo 2.8.1, 3.3.3, 4.0.1. Check the vendor advisory for mitigations.

References

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