{"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_01M5KFV2ZFY834QJ2YJ9480GX2","modified_at":"2026-07-08T06:00:54.217433740Z","published_at":"2021-06-01T21:19:32Z","references":["https://osv.dev/vulnerability/GHSA-q2q7-5pp4-w6pg","https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg","https://nvd.nist.gov/vuln/detail/CVE-2021-33503","https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec","https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65","https://github.com/advisories/GHSA-q2q7-5pp4-w6pg","https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml","https://github.com/urllib3/urllib3","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73","https://security.gentoo.org/glsa/202107-36","https://www.oracle.com/security-alerts/cpuoct2021.html"],"severity":{"label":"high","score":7.5},"sources":[{"source":"osv","source_id":"GHSA-q2q7-5pp4-w6pg","url":"https://osv.dev/vulnerability/GHSA-q2q7-5pp4-w6pg"}],"summary":"Catastrophic backtracking in URL authority parser when passed URL containing many @ characters"}