{"id":"CVE-2026-49477","aliases":["GHSA-836r-79rf-4m37","PYSEC-2026-3072"],"url":"https://o3.security/vulnerability/CVE-2026-49477","summary":"Soup Sieve: Regular Expression Denial of Service (ReDoS) in soupsieve Selector Parser","details":"Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.8.4, the CSS selector parser in soupsieve contains a regular expression vulnerable to catastrophic backtracking when processing an attribute selector with an unterminated quoted value in soupsieve/css_parser.py, allowing an attacker who can supply untrusted CSS selector strings to soupsieve.compile() or Beautiful Soup .select() / .select_one() to cause CPU exhaustion and denial of service. This issue is fixed in version 2.8.4.","published":"2026-07-14T20:51:29.369Z","modified":"2026-08-12T03:51:13.706219171Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00522,"percentile":0.42051,"asOf":"2026-08-29"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"soupsieve","fixedVersion":"2.8.4"}],"fix":{"url":"https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043b728217dc3","label":"facelessuser/soupsieve@eb43976"},"references":[{"type":"WEB","url":"https://github.com/facelessuser/soupsieve/releases/tag/2.8.4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49477.json"},{"type":"ADVISORY","url":"https://github.com/facelessuser/soupsieve/security/advisories/GHSA-836r-79rf-4m37"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49477"},{"type":"FIX","url":"https://github.com/facelessuser/soupsieve/commit/eb4397618709186c109400448c6043b728217dc3"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:13.706219171Z"}}