{"action":"Upgrade urllib3 to 1.26.5 or later.","affected":[{"fixed":"1.26.5","introduced":"1.25.4"}],"component":"urllib3","cve_ids":["CVE-2021-33503"],"ecosystem":"PyPI","epss":0.03273,"exploited":false,"fixed_versions":["1.26.5"],"ghsa_id":"GHSA-q2q7-5pp4-w6pg","id":"tcs_01M5KGB2GE8MQTV3JP9G942R5B","modified_at":"2026-10-13T09:30:02.842062535Z","published_at":"2021-06-29T11:15:00Z","references":["https://osv.dev/vulnerability/PYSEC-2021-108","https://github.com/advisories/GHSA-q2q7-5pp4-w6pg","https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"],"severity":{"label":"unknown"},"sources":[{"source":"osv","source_id":"PYSEC-2021-108","url":"https://osv.dev/vulnerability/PYSEC-2021-108"}],"summary":"An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component, the authority regular expression exhibits catastrophic backtracking,"}