CVE-2020-5236

EIP tracks 1 public exploit for CVE-2020-5236. PoCs published by motikan2010.

AI-analyzed exploit summary This repository contains a functional proof-of-concept for CVE-2020-5236, a ReDoS vulnerability in Waitress 1.4.2. The exploit demonstrates how a malformed header with invalid characters triggers catastrophic backtracking in the regex engine, causing 100% CPU usage and a denial of service.

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.