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.
Project Subscriptions
| Vendors | Products |
|---|---|
|
Fedoraproject
Subscribe
|
|
|
Netapp
Subscribe
|
|
|
Python
Subscribe
|
Python
Subscribe
|
|
Redhat
Subscribe
|
Codeready Linux Builder
Subscribe
Codeready Linux Builder For Ibm Z Systems
Subscribe
Codeready Linux Builder For Power Little Endian
Subscribe
Enterprise Linux
Subscribe
Enterprise Linux Eus
Subscribe
Enterprise Linux For Ibm Z Systems
Subscribe
Enterprise Linux For Ibm Z Systems Eus
Subscribe
Enterprise Linux For Power Little Endian
Subscribe
Enterprise Linux For Power Little Endian Eus
Subscribe
Enterprise Linux Server Aus
Subscribe
Enterprise Linux Server For Power Little Endian Update Services For Sap Solutions
Subscribe
Enterprise Linux Server Tus
Subscribe
Enterprise Linux Server Update Services For Sap Solutions
Subscribe
Rhel Software Collections
Subscribe
|
Advisories
| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-2808-1 | python3.5 security update |
Debian DLA |
DLA-3432-1 | python2.7 security update |
Debian DLA |
DLA-3477-1 | python3.7 security update |
Debian DLA |
DLA-3980-1 | python3.9 security update |
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 |
USN-5083-1 | Python vulnerabilities |
Ubuntu USN |
USN-5199-1 | Python vulnerabilities |
Ubuntu USN |
USN-5200-1 | Python vulnerabilities |
Ubuntu USN |
USN-6891-1 | Python vulnerabilities |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Mon, 03 Nov 2025 22:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Projects
Sign in to view the affected projects.
Status: PUBLISHED
Assigner: redhat
Published:
Updated: 2025-11-03T21:45:06.299Z
Reserved: 2021-08-23T00:00:00.000Z
Link: CVE-2021-3733
No data.
Status : Modified
Published: 2022-03-10T17:42:59.623
Modified: 2025-11-03T22:15:50.833
Link: CVE-2021-3733
OpenCVE Enrichment
No data.
Weaknesses
Debian DLA
EUVD
Ubuntu USN