CVE-2020-8492

Name: CVE-2020-8492
Creator: NVD / NIST
Published: 2020-01-30T19:15:12.103+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 6.62%

Last modified Jun 17, 2026

CVE-2020-8492 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking.. EPSS estimates a 6.62% chance of exploitation in the next 30 days.

Description

Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS Probability

6.62%

93.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-400

Affected Software

Vendor	Product	Versions
Python	Python	>= 2.7.0, <= 2.7.17
Python	Python	>= 3.5.0, <= 3.5.9
Python	Python	>= 3.6.0, <= 3.6.10
Python	Python	>= 3.7.0, <= 3.7.6
Python	Python	>= 3.8.0, <= 3.8.1
Opensuse	Leap	15.1
Canonical	Ubuntu Linux	12.04
Canonical	Ubuntu Linux	14.04
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	19.10
Canonical	Ubuntu Linux	20.04
Fedoraproject	Fedora	31
Fedoraproject	Fedora	32
Debian	Debian Linux	9.0

References

http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00003.htmlThird Party Advisory
https://bugs.python.org/issue39503Issue Tracking, Vendor Advisory
https://github.com/python/cpython/pull/18284Patch, Third Party Advisory
https://lists.apache.org/thread.html/rdb31a608dd6758c6093fd645aea3fbf022dd25b37109b6aaea5bc0b5%40%3Ccommits.cassandra.apache.org%3E
https://lists.apache.org/thread.html/rfec113c733162b39633fd86a2d0f34bf42ac35f711b3ec1835c774da%40%3Ccommits.cassandra.apache.org%3E
https://lists.debian.org/debian-lts-announce/2020/07/msg00011.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7WOKDEXLYW5UQ4S7PA7E37IITOC7C56J/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A5NSAX4SC3V64PGZUPH7PRDLSON34Q5A/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APGWEMYZIY5VHLCSZ3HD67PA5Z2UQFGH/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UESGYI5XDAHJBATEZN3MHNDUBDH47AS6/
https://python-security.readthedocs.io/vuln/urllib-basic-auth-regex.htmlExploit, Third Party Advisory
https://security.gentoo.org/glsa/202005-09Third Party Advisory
https://security.netapp.com/advisory/ntap-20200221-0001/Third Party Advisory
https://usn.ubuntu.com/4333-1/Third Party Advisory
https://usn.ubuntu.com/4333-2/Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00003.htmlThird Party Advisory
https://bugs.python.org/issue39503Issue Tracking, Vendor Advisory
https://github.com/python/cpython/pull/18284Patch, Third Party Advisory
https://lists.apache.org/thread.html/rdb31a608dd6758c6093fd645aea3fbf022dd25b37109b6aaea5bc0b5%40%3Ccommits.cassandra.apache.org%3E
https://lists.apache.org/thread.html/rfec113c733162b39633fd86a2d0f34bf42ac35f711b3ec1835c774da%40%3Ccommits.cassandra.apache.org%3E
https://lists.debian.org/debian-lts-announce/2020/07/msg00011.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7WOKDEXLYW5UQ4S7PA7E37IITOC7C56J/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A5NSAX4SC3V64PGZUPH7PRDLSON34Q5A/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APGWEMYZIY5VHLCSZ3HD67PA5Z2UQFGH/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UESGYI5XDAHJBATEZN3MHNDUBDH47AS6/
https://python-security.readthedocs.io/vuln/urllib-basic-auth-regex.htmlExploit, Third Party Advisory
https://security.gentoo.org/glsa/202005-09Third Party Advisory
https://security.netapp.com/advisory/ntap-20200221-0001/Third Party Advisory
https://usn.ubuntu.com/4333-1/Third Party Advisory
https://usn.ubuntu.com/4333-2/Third Party Advisory

Timeline

Published: Jan 30, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-8492?

How severe is CVE-2020-8492?

CVE-2020-8492 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 6.62% probability of exploitation in the next 30 days.

How do I fix CVE-2020-8492?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-8492?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST