What’s Vulnerable › Vulnerabilities

CVE-2026-69153: PostCSS: incomplete fix of CVE-2026-45623 — attacker-controlled sourceMappingURL reads arbitrary .map files when `from` is unset

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-08-03 · updated 2026-08-05
• Weakness: CWE-22

Description

PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. Prior to 8.5.19, if from is unset, an attacker can cause PreviousMap.loadFile() to read an unintended source-map file by supplying an absolute or directory-traversal sourceMappingURL. The resulting map’s sources and sourcesContent may then be exposed to the application. This issue is fixed in version 8.5.19.

Affected products

• postcss: before 8.5.23 — fixed in 8.5.23
• Npm Postcss: before 8.5.23 — fixed in 8.5.23

How to fix

Upgrade to a fixed version: postcss 8.5.23; Npm Postcss 8.5.23. Check the vendor advisory for mitigations.

References

• https://github.com/postcss/postcss/commit/7beca139e70f9075c6b19700fcb00dd8033e5da8
• https://github.com/postcss/postcss/releases/tag/8.5.19
• https://github.com/postcss/postcss/security/advisories/GHSA-fxqj-rqcc-2cmp
• https://github.com/postcss/postcss/security/advisories/GHSA-fxqj-rqcc-2cmp

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