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.
Published: 2022-03-07
Score: 6.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-2808-1 python3.5 security update
Debian DLA Debian DLA DLA-3432-1 python2.7 security update
Debian DLA Debian DLA DLA-3477-1 python3.7 security update
Debian DLA Debian DLA DLA-3980-1 python3.9 security update
EUVD EUVD EUVD-2021-27010 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.
Ubuntu USN Ubuntu USN USN-5083-1 Python vulnerabilities
Ubuntu USN Ubuntu USN USN-5199-1 Python vulnerabilities
Ubuntu USN Ubuntu USN USN-5200-1 Python vulnerabilities
Ubuntu USN Ubuntu USN USN-6891-1 Python vulnerabilities
History

Mon, 03 Nov 2025 22:30:00 +0000

Type Values Removed Values Added
References

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2025-11-03T21:45:06.299Z

Reserved: 2021-08-23T00:00:00.000Z

Link: CVE-2021-3733

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2022-03-10T17:42:59.623

Modified: 2025-11-03T22:15:50.833

Link: CVE-2021-3733

cve-icon Redhat

Severity : Moderate

Publid Date: 2021-08-10T00:00:00Z

Links: CVE-2021-3733 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses