CVE-2020-5236

Severity CVSS v4.0:

Pending analysis

Type:

CWE-400 Uncontrolled Resource Consumption ('Resource Exhaustion')

Publication date:

04/02/2020

Last modified:

06/02/2020

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.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 6.50 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x

6.50

Severity 3.x

MEDIUM

Vector 2.0

AV:N/AC:L/Au:S/C:N/I:N/A:C CVSS v2.0 Severity and Metrics:

Base Score: 6.80 MEDIUM
Vector: AV:N/AC:L/Au:S/C:N/I:N/A:C

Attack Vector (AV): Network
Attack Complexity (AC): Low
Authentication (Au): Single
Confidentiality (C): None
Integrity (I): None
Availability (A): Complete