{"id":"EUVD-2026-91741","revision":null,"records":[{"revision":"03b3b352af6a4e0eafba28873afef187","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-104844","aliases":[],"title":"PostCSS: Quadratic complexity in flat selector parsing allows CPU exhaustion","description":"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.","state":0,"publishedAt":"2026-10-02T15:43:14.082+00:00","modifiedAt":"2026-10-02T16:16:45.99+00:00","affected":[{"ecosystem":"Vendor product","name":"postcss-selector-parser","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"postcss\",\n                    \"product\": \"postcss-selector-parser\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 7.1.6\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","score":5.9,"severity":"MEDIUM"}],"references":["https://github.com/postcss/postcss-selector-parser/security/advisories/GHSA-rj75-hqrm-r3gf","https://github.com/postcss/postcss-selector-parser/commit/62b191792df0a0bc56062e5a875bc74aae2a51cd","https://github.com/postcss/postcss-selector-parser/releases/tag/7.1.6"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-104844","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-104844","identifiers":["CVE-2026-104844"]},"retained":false,"historicalAffected":[]},{"revision":"5e9672ac3d944805a1760b427c59a528","observedAt":"2026-10-28T00:47:25.339+00:00","statement":{"source":"euvd","id":"EUVD-2026-91741","aliases":["CVE-2026-104844","GHSA-rj75-hqrm-r3gf"],"title":"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 …","description":"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.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","score":5.9,"severity":null}],"references":["https://github.com/postcss/postcss-selector-parser/security/advisories/GHSA-rj75-hqrm-r3gf","https://github.com/postcss/postcss-selector-parser/commit/62b191792df0a0bc56062e5a875bc74aae2a51cd","https://github.com/postcss/postcss-selector-parser/releases/tag/7.1.6"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-91741","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Oct 2, 2026, 3:43:14 PM","dateUpdated":"Oct 2, 2026, 4:16:45 PM"},"relatedAdvisories":[{"id":"openSUSE-SU-2026:12083-1","title":"git-bug-0.11.0-2.1 on GA media","vulnerabilityIds":["CVE-2026-104844"]}],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-91741","identifiers":["EUVD-2026-91741","CVE-2026-104844","GHSA-rj75-hqrm-r3gf"]},"retained":false,"historicalAffected":[]},{"revision":"a68a7065735b47b39eaccc17f3b2eec5","observedAt":"2026-10-25T04:17:29.458+00:00","statement":{"source":"nvd","id":"CVE-2026-104844","aliases":[],"title":"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 …","description":"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.","state":0,"publishedAt":"2026-10-02T16:16:46.917+00:00","modifiedAt":"2026-10-02T18:44:11.27+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","score":5.9,"severity":"MEDIUM"}],"references":["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"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-104844","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Awaiting Analysis","weaknesses":["CWE-400","CWE-407"],"productCriteria":[],"sourceDates":{"published":"2026-10-02T16:16:46.917","lastModified":"2026-10-02T18:44:11.270"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-104844","identifiers":["CVE-2026-104844"]},"retained":false,"historicalAffected":[]},{"revision":"553a7dfd2d9a4e7ab69d67a66192a82f","observedAt":"2026-10-26T15:35:41.018+00:00","statement":{"source":"osv","id":"GHSA-rj75-hqrm-r3gf","aliases":["CVE-2026-104844"],"title":"PostCSS: Quadratic complexity in flat selector parsing allows CPU exhaustion","description":"### Impact\n\n`.` and `#` are not word delimiters in the tokenizer, so a flat selector such as\n`.a.a.a...` reaches `splitWord()` as a single word token carrying n class or id\nindexes. Three passes scanned those index arrays linearly for every index,\nmaking the parse O(n^2) in the number of indexes rather than in input length:\n`uniqs()`, the `indices.forEach` loop, and the Sass-interpolation filter.\nParsing a 400 KB flat selector took ~34 s on a modern laptop, fully occupying a\nsingle thread. A benign selector of identical byte size parses in tens of\nmilliseconds, so the cost is driven by the index count, not the input size.\nThe nesting depth of such a selector is 0, so the `maxNestingDepth` guard added\nin 7.1.3 offers no protection.\n\nReachability is deployment dependent. Only consumers that parse untrusted,\nattacker-supplied selectors synchronously in a request path are exposed, for\nexample CSS sanitizers, CSS-in-JS services and online playgrounds. Ordinary\nbuild-time use on trusted sources is not affected.\n\n### Patches\n\nFixed in 7.1.6. The three passes now use Set membership tests, making parsing\nlinear in the number of indexes. There is no behaviour change: parsing is\nbyte-identical on a differential corpus of 8413 selectors.\n\n### Workarounds\n\nCap the size of selectors accepted from untrusted sources before parsing.","state":0,"publishedAt":"2026-10-05T22:53:54+00:00","modifiedAt":"2026-10-26T14:16:59.9215408+00:00","affected":[{"ecosystem":"npm","name":"postcss-selector-parser","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"7.0.0"},{"kind":"fixed","version":"7.1.6"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"npm","name":"postcss-selector-parser","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"6.1.5"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/postcss/postcss-selector-parser/security/advisories/GHSA-rj75-hqrm-r3gf","https://nvd.nist.gov/vuln/detail/CVE-2026-104844","https://github.com/postcss/postcss-selector-parser/pull/346","https://github.com/postcss/postcss-selector-parser/commit/62b191792df0a0bc56062e5a875bc74aae2a51cd","https://github.com/postcss/postcss-selector-parser/commit/70b0779c843462197380d25daa02d1528bf7eae5","https://github.com/postcss/postcss-selector-parser","https://github.com/postcss/postcss-selector-parser/releases/tag/6.1.5","https://github.com/postcss/postcss-selector-parser/releases/tag/7.1.6"],"sourceUrl":"https://github.com/advisories/GHSA-rj75-hqrm-r3gf","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-rj75-hqrm-r3gf","identifiers":["GHSA-rj75-hqrm-r3gf","CVE-2026-104844"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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