CVE-2026-104844: PostCSS: Quadratic complexity in flat selector parsing allows CPU exhaustion
postcss · postcss-selector-parser
Affected: postcss-selector-parser · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 33% of scored CVEs
DescriptionCVE.org
PostCSS Selector Parser is a CSS selector parser that integrates with PostCSS but does not require it. Prior to 7.1.6, src/parser.js splitWord() can receive a flat selector as one word token carrying many class or ID indexes because period and hash characters are not tokenizer word delimiters. The uniqs() deduplication and per-index class and ID membership checks repeatedly scan the class and ID index arrays, while a separate Sass-interpolation filtering pass also performs repeated linear scanning. Together, these passes make parsing quadratic in the number of indexes and allow a crafted selector to occupy a synchronous parser thread. The maxNestingDepth guard does not mitigate the issue because the hostile selector can have zero nesting depth. Only consumers that synchronously parse untrusted selectors in an exposed request path are affected; ordinary build-time parsing of trusted sources is not affected. This issue is fixed in version 7.1.6.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- postcss · postcss-selector-parser< 7.1.6
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- postcss
- Published
- October 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-104844 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.