What’s Vulnerable › Vulnerabilities

CVE-2021-29059: ReDOS in IS-SVG

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-06-21 · updated 2026-06-17
• Weakness: CWE-770

Description

A vulnerability was discovered in IS-SVG version 2.1.0 to 4.2.2 and below where a Regular Expression Denial of Service (ReDOS) occurs if the application is provided and checks a crafted invalid SVG string.

Affected products

• Is-Svg Project Is-Svg: from 2.1.0 before 4.3.0 — fixed in 4.3.0
• Npm Is-Svg: from 2.1.0 before 4.3.0 — fixed in 4.3.0

How to fix

Upgrade to a fixed version: Is-Svg Project Is-Svg 4.3.0; Npm Is-Svg 4.3.0. Check the vendor advisory for mitigations.

References

• https://github.com/sindresorhus/is-svg/releases/tag/v4.3.0
• https://github.com/yetingli/PoCs/blob/main/CVE-2021-29059/IS-SVG.md
• https://github.com/yetingli/SaveResults/blob/main/js/is-svg.js
• https://www.npmjs.com/package/is-svg
• https://github.com/sindresorhus/is-svg/releases/tag/v4.3.0
• https://github.com/yetingli/PoCs/blob/main/CVE-2021-29059/IS-SVG.md
• https://github.com/yetingli/SaveResults/blob/main/js/is-svg.js
• https://www.npmjs.com/package/is-svg

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