Vulnerability in PostCSS Selector Parser Affects Multiple CSS Implementations
CVE-2026-104844

5.9MEDIUM

Key Information:

Vendor

Postcss

Status
Postcss-selector-parser
Vendor
CVE Published:
2 October 2026

What is CVE-2026-104844?

The PostCSS Selector Parser, prior to version 7.1.6, is susceptible to a Denial of Service vulnerability. This occurs due to improper handling of selectors, allowing an attacker to craft a selector that consumes excessive processing resources. Specifically, the issue lies in the splitWord() function, which fails to treat separator characters correctly, leading to inflated processing time. The repeated scanning of class and ID index arrays, combined with a separate filtering pass, results in quadratic parsing complexity. This vulnerability affects consumers that synchronously parse untrusted selectors during an exposed request, while safe parsing of trusted sources at build time remains unaffected. The issue has been addressed in version 7.1.6.

Affected Version(s)

postcss-selector-parser < 7.1.6

References

https://github.com/postcss/postcss-selector-parser/securi...
x_refsource_CONFIRM
https://github.com/postcss/postcss-selector-parser/commit...
x_refsource_MISC
https://github.com/postcss/postcss-selector-parser/releas...
x_refsource_MISC

CVSS V3.1

Score:
5.9
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.