CVE-2020-5236
Published: 4 February 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.
Notes
Author | Note |
---|---|
mdeslaur | introduced in 1.4.2 |
Priority
Status
Package | Release | Status |
---|---|---|
waitress Launchpad, Ubuntu, Debian |
bionic |
Not vulnerable
(code not present)
|
eoan |
Not vulnerable
(code not present)
|
|
trusty |
Does not exist
|
|
upstream |
Needs triage
|
|
xenial |
Not vulnerable
(code not present)
|
|
Patches: upstream: https://github.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1f |
Severity score breakdown
Parameter | Value |
---|---|
Base score | 6.5 |
Attack vector | Network |
Attack complexity | Low |
Privileges required | Low |
User interaction | None |
Scope | Unchanged |
Confidentiality | None |
Integrity impact | None |
Availability impact | High |
Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |