What’s Vulnerable › Vulnerabilities

CVE-2023-44270: PostCSS line return parsing error

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-09-29 · updated 2026-06-17
• Weakness: CWE-74

Description

An issue was discovered in PostCSS before 8.4.31. The vulnerability affects linters using PostCSS to parse external untrusted CSS. An attacker can prepare CSS in such a way that it will contains parts parsed by PostCSS as a CSS comment. After processing by PostCSS, it will be included in the PostCSS output in CSS nodes (rules, properties) despite being included in a comment.

Affected products

• postcss: before 8.4.31 — fixed in 8.4.31
• Npm Postcss: before 8.4.31 — fixed in 8.4.31

How to fix

Upgrade to a fixed version: postcss 8.4.31; Npm Postcss 8.4.31. Check the vendor advisory for mitigations.

References

• https://github.com/github/advisory-database/issues/2820
• https://github.com/postcss/postcss/blob/main/lib/tokenize.js#L25
• https://github.com/postcss/postcss/commit/58cc860b4c1707510c9cd1bc1fa30b423a9ad6c5
• https://github.com/postcss/postcss/releases/tag/8.4.31
• https://github.com/github/advisory-database/issues/2820
• https://github.com/postcss/postcss/blob/main/lib/tokenize.js#L25
• https://github.com/postcss/postcss/commit/58cc860b4c1707510c9cd1bc1fa30b423a9ad6c5
• https://github.com/postcss/postcss/releases/tag/8.4.31
• https://lists.debian.org/debian-lts-announce/2024/12/msg00025.html

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