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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database

Vulnerability Change Records for CVE-2020-5236

Change History

CVE Modified by GitHub, Inc. 2/03/2020 11:15:10 PM

Action Type Old Value New Value
Changed 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.
 
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.