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CVE-2020-5236

5.7 · MEDIUM

Waitress version 1.4.2 allows a DOS attack When waitress receives a header that contains invalid characters.

Published Feb 4, 2020CWE-400EPSS 2.36%

Overview

CVE-2020-5236 is a medium-severity vulnerability. It was published on February 4, 2020 and has a CVSS 3.1 base score of 5.7 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.7, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

Waitress version 1.4.2 allows a DOS attack When waitress receives a header that contains invalid characters. When a header like "Bad-header: xxxxxxxxxxxxxxx\x10" is received, it will cause the regular expression engine to catastrophically backtrack causing the process to use 100% CPU time and blocking any other interactions. This allows an attacker to send a single request with an invalid header and take the service offline. This issue was introduced in version 1.4.2 when the regular expression was updated to attempt to match the behaviour required by errata associated with RFC7230. The regular expression that is used to validate incoming headers has been updated in version 1.4.3, it is recommended that people upgrade to the new version of Waitress as soon as possible.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1fGitHubgithub.com/Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgcGitHubgithub.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1fGitHubgithub.com/Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgc

How CyberStrike helps

Frequently asked questions

What is CVE-2020-5236?

CVE-2020-5236 is a medium-severity vulnerability. It was published on February 4, 2020 and has a CVSS 3.1 base score of 5.7 (MEDIUM).

How severe is CVE-2020-5236?

This vulnerability has a CVSS 3.1 base score of 5.7, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2020-5236?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2020-5236?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2020-5236 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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