{"cve":"CVE-2026-86000","nvd":{"published":"2026-09-17T16:18:16.757","modified":"2026-09-30T17:51:36.337","status":"Awaiting Analysis","description":"Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.9, the selector parser in src/soupsieve/css_parser.py defines IDENTIFIER with adjacent quantified groups over overlapping character classes, and VALUE embeds IDENTIFIER for attribute selectors. When an attacker-controlled selector contains a long identifier or unquoted attribute-value run followed by input that makes the overall match fail, the regular expression engine explores quadratically many splits between the overlapping groups. User-controlled selectors can reach this path through soupsieve.compile(), soupsieve.select(), or BeautifulSoup.select(), while applications using only hard-coded selectors are unaffected. The resulting CPU consumption can hold the Python GIL, exhaust application workers, and stall a service; successful plain identifier matches are linear, and the issue does not cause memory corruption or code execution. The issue is fixed in version 2.9.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-400","CWE-1333"],"references":["https://github.com/facelessuser/soupsieve/commit/ce44e4996e6632871c18cdd7a7fb641be8ef34ef","https://github.com/facelessuser/soupsieve/releases/tag/2.9","https://github.com/facelessuser/soupsieve/security/advisories/GHSA-gjv8-xp57-g29c","https://github.com/facelessuser/soupsieve/security/advisories/GHSA-gjv8-xp57-g29c"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-86000","score":0.00609,"percentile":0.4885,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-gjv8-xp57-g29c","url":"https://osv.dev/vulnerability/GHSA-gjv8-xp57-g29c","summary":"Soup Sieve: Polynomial-time ReDoS (O(n²)) in the `IDENTIFIER` / `VALUE` selector sub-patterns","modified":"2026-10-01T17:56:08.291385035Z","packages":[{"ecosystem":"PyPI","name":"soupsieve","purl":"pkg:pypi/soupsieve","ranges":["<2.9.0"],"fixed":["2.9.0"]}]},{"id":"PYSEC-2026-4170","url":"https://osv.dev/vulnerability/PYSEC-2026-4170","summary":"Soup Sieve: Polynomial-time ReDoS (O(n²)) in the `IDENTIFIER` / `VALUE` selector sub-patterns","modified":"2026-10-01T17:45:17.856132762Z","packages":[{"ecosystem":"PyPI","name":"soupsieve","purl":"pkg:pypi/soupsieve","ranges":["<2.9.0"],"fixed":["2.9.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}