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

> Attackers can cause denial of service in SVGO by submitting malicious SVG files with entity expansion, leading to application crashes.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Mar 2026
- **Updated:** 10 Sep 2026
- **Also known as:** CLSA-2026-1779324470, DEBIAN-CVE-2026-29074, GHSA-xpqw-6gx7-v673, ROOT-APP-NPM-CVE-2026-29074

## What is CVE-2026-29074?

CVE-2026-29074 is a high-severity denial of service vulnerability in svgo, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-776 (Improper Restriction of Recursive Entity References in DTDs)

## Which versions are affected by CVE-2026-29074?

6 open source packages ship an affected version, including svgo. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `svgo` | npm | From 2.1.0 | 2.8.1 |
| `svgo` | npm | From 2.1.0 | 2.8.1 |
| `svgo` | npm | From 3.0.0 | 3.3.3 |
| `svgo` | npm | From 3.0.0 | 3.3.3 |
| `svgo` | npm | From 4.0.0 | 4.0.1 |
| `svgo` | npm | From 4.0.0 | 4.0.1 |

Products: Svgo Svgo.

## How do I fix CVE-2026-29074?

Upgrade svgo to a fixed version for your release line: 2.8.1, 3.3.3 or 4.0.1.

## Is CVE-2026-29074 being exploited?

There is no known exploitation of CVE-2026-29074 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-29074 and fix it if it is affected.

What it is: CVE-2026-29074 is a high-severity denial of service vulnerability in svgo, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-29074 in the wild and no public exploit code.

Affected packages and fixed versions:
- svgo (npm): affected from 2.1.0; fixed in 2.8.1
- svgo (npm): affected from 2.1.0; fixed in 2.8.1
- svgo (npm): affected from 3.0.0; fixed in 3.3.3
- svgo (npm): affected from 3.0.0; fixed in 3.3.3
- svgo (npm): affected from 4.0.0; fixed in 4.0.1
- svgo (npm): affected from 4.0.0; fixed in 4.0.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-29074/ (Markdown: https://insights.sbomify.com/CVE-2026-29074/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-29074
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-29074
- OSV: https://osv.dev/vulnerability/CVE-2026-29074

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-29074/
Summaries are generated and may contain mistakes; the official description above is the record.