{"id":"CVE-2021-3733","revision":"4fd045adea1e4c9e84dfc74bde81c925","records":[{"revision":"4fd045adea1e4c9e84dfc74bde81c925","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2021-3733","aliases":[],"title":"There's a flaw in urllib's AbstractBasicAuthHandler class. An attacker who controls a malicious HTTP server that an HTTP client (such as web browser) connects to, could trigger a Regular Expression Denial of Service (ReDOS) during an authen…","description":"There's a flaw in urllib's AbstractBasicAuthHandler class. An attacker who controls a malicious HTTP server that an HTTP client (such as web browser) connects to, could trigger a Regular Expression Denial of Service (ReDOS) during an authentication request with a specially crafted payload that is sent by the server to the client. The greatest threat that this flaw poses is to application availability.","state":0,"publishedAt":"2022-03-07T00:00:00+00:00","modifiedAt":"2026-10-14T09:49:49.275+00:00","affected":[{"ecosystem":"Vendor product","name":"python","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"n/a\",\n                    \"product\": \"python\",\n                    \"versions\": [\n                        {\n                            \"version\": \"Fixed in python v3.6.14, python v3.7.11, python v3.8.10, python v3.9.5.\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://bugs.python.org/issue43075","https://bugzilla.redhat.com/show_bug.cgi?id=1995234","https://github.com/python/cpython/pull/24391","https://ubuntu.com/security/CVE-2021-3733","https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb","https://security.netapp.com/advisory/ntap-20220407-0001/","https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html","https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2021-3733","license":"CVE Program Terms of Use","key":"cve-program:CVE-2021-3733","identifiers":["CVE-2021-3733"]},"retained":false,"historicalAffected":[]}],"coverage":[]}