{"cve":"CVE-2021-3733","nvd":{"published":"2022-03-10T17:42:59.623","modified":"2026-10-14T10:17:47.417","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":6.5},"cwes":["CWE-400"],"references":["https://bugs.python.org/issue43075","https://bugzilla.redhat.com/show_bug.cgi?id=1995234","https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb","https://github.com/python/cpython/pull/24391","https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html"],"products":["fedoraproject:extra_packages_for_enterprise_linux","fedoraproject:fedora","netapp:hci_compute_node_firmware","netapp:management_services_for_element_software_and_netapp_hci","netapp:ontap_select_deploy_administration_utility","netapp:solidfire\\,_enterprise_sds_\\&_hci_storage_node","python:python","redhat:codeready_linux_builder","redhat:codeready_linux_builder_for_ibm_z_systems","redhat:codeready_linux_builder_for_power_little_endian","redhat:enterprise_linux","redhat:enterprise_linux_eus","redhat:enterprise_linux_for_ibm_z_systems","redhat:enterprise_linux_for_ibm_z_systems_eus","redhat:enterprise_linux_for_power_little_endian","redhat:enterprise_linux_for_power_little_endian_eus","redhat:enterprise_linux_server_aus","redhat:enterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions","redhat:enterprise_linux_server_tus","redhat:enterprise_linux_server_update_services_for_sap_solutions"],"source":"nvd","synced_at":"2026-10-19T21:28:04.509275555+00:00"},"epss":{"cve":"CVE-2021-3733","score":0.04799,"percentile":0.91882,"date":"2026-10-25"},"kev":null,"osv":[],"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."]}