CVE-2021-3733

6.5 MEDIUM
Published: March 10, 2022 Modified: November 03, 2025

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.

AI Explanation

Get an AI-powered plain-language explanation of this vulnerability and remediation steps.

Login to generate AI explanation

CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://bugs.python.org/issue43075
Source: secalert@redhat.com
Exploit Issue Tracking Patch Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1995234
Source: secalert@redhat.com
Issue Tracking Third Party Advisory
https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb
Source: secalert@redhat.com
Patch Third Party Advisory
https://github.com/python/cpython/pull/24391
Source: secalert@redhat.com
Patch Third Party Advisory
https://security.netapp.com/advisory/ntap-20220407-0001/
Source: secalert@redhat.com
Third Party Advisory
https://ubuntu.com/security/CVE-2021-3733
Source: secalert@redhat.com
Patch Third Party Advisory
https://bugs.python.org/issue43075
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Issue Tracking Patch Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1995234
Source: af854a3a-2127-422b-91ae-364da2661108
Issue Tracking Third Party Advisory
https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb
Source: af854a3a-2127-422b-91ae-364da2661108
Patch Third Party Advisory
https://github.com/python/cpython/pull/24391
Source: af854a3a-2127-422b-91ae-364da2661108
Patch Third Party Advisory
https://security.netapp.com/advisory/ntap-20220407-0001/
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://ubuntu.com/security/CVE-2021-3733
Source: af854a3a-2127-422b-91ae-364da2661108
Patch Third Party Advisory

17 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.7%
71th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

netapp fedoraproject redhat python