CVE-2026-104844

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.

CVSS v3 5.9 MEDIUM

5.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/postcss/postcss-selector-parser/commit/62b191792df0a0bc56062e5a875bc74aae2a51cd
https://github.com/postcss/postcss-selector-parser/releases/tag/7.1.6
https://github.com/postcss/postcss-selector-parser/security/advisories/GHSA-rj75-hqrm-r3gf

Configurations

No configuration.

History

02 Oct 2026, 16:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-02 16:16

Updated : 2026-10-02 18:44

NVD link : CVE-2026-104844

Mitre link : CVE-2026-104844

CVE.ORG link : CVE-2026-104844

JSON object : View

Products Affected

No product.

CWE

CWE-400

Uncontrolled Resource Consumption

CWE-407

Inefficient Algorithmic Complexity

{"id": "CVE-2026-104844", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-104844", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-02T16:16:26.803770Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.9, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 2.2}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "postcss", "product": "postcss-selector-parser", "versions": [{"status": "affected", "version": "< 7.1.6"}]}]}], "published": "2026-10-02T16:16:46.917", "references": [{"url": "https://github.com/postcss/postcss-selector-parser/commit/62b191792df0a0bc56062e5a875bc74aae2a51cd", "source": "security-advisories@github.com"}, {"url": "https://github.com/postcss/postcss-selector-parser/releases/tag/7.1.6", "source": "security-advisories@github.com"}, {"url": "https://github.com/postcss/postcss-selector-parser/security/advisories/GHSA-rj75-hqrm-r3gf", "source": "security-advisories@github.com"}], "vulnStatus": "Awaiting Analysis", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-400"}, {"lang": "en", "value": "CWE-407"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2026-10-02T18:44:11.270", "sourceIdentifier": "security-advisories@github.com"}