CVE-2020-5236

2020-02-0400:00:00

ubuntu.com

6.8 Medium

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

SINGLE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

COMPLETE

AV:N/AC:L/Au:S/C:N/I:N/A:C

6.5 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

0.001 Low

EPSS

Percentile

33.0%

JSON

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.