CVE-2021-3733

Public Exploit

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.

Category

6.5
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.44%
Vendor Advisory python.org
Affected: n/a python
Published at:
Updated at:

References

Link Tags
https://bugs.python.org/issue43075 issue tracking patch vendor advisory exploit
https://bugzilla.redhat.com/show_bug.cgi?id=1995234 issue tracking third party advisory
https://github.com/python/cpython/pull/24391 third party advisory patch
https://ubuntu.com/security/CVE-2021-3733 third party advisory patch
https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb third party advisory patch
https://security.netapp.com/advisory/ntap-20220407-0001/ third party advisory
https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html mailing list
https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html mailing list

Frequently Asked Questions

What is the severity of CVE-2021-3733?
CVE-2021-3733 has been scored as a medium severity vulnerability.
How to fix CVE-2021-3733?
To fix CVE-2021-3733, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-3733 being actively exploited in the wild?
It is possible that CVE-2021-3733 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-3733?
CVE-2021-3733 affects n/a python.
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