CVE-2020-5236
February 04, 2020
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.
Affected Packages
waitress (PYTHON):
Affected version(s) =1.4.2 <1.4.3Fix Suggestion:
Update to version 1.4.3Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
PASSIVE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.7
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
CVSS v2
Base Score:
6.8
Access Vector
NETWORK
Access Complexity
LOW
Authentication
SINGLE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
Weakness Type (CWE)
Uncontrolled Resource Consumption
EPSS
Base Score:
13.92
