CVE-2020-5236
Waitress Regular Expression Denial of Service (ReDoS)
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.
INFO
Published Date :
Feb. 4, 2020, 3:15 a.m.
Last Modified :
Feb. 6, 2020, 6:46 p.m.
Source :
[email protected]
Remotely Exploitable :
Yes !
Impact Score :
3.6
Exploitability Score :
2.8
Public PoC/Exploit Available at Github
CVE-2020-5236 has a 7 public PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2020-5236.
| URL | Resource |
|---|---|
| https://github.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1f | Patch Third Party Advisory |
| https://github.com/Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgc | Third Party Advisory |
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Fetches security vulnerabilities and creates pip-constraints based on them.
python security dependencies pip supply-chain-security
Python Shell
None
List of RegEx DoS (ReDoS) CVEs and resources
security awesome redos regex dos regex-dos pentesting awesome-list regex-security
None
None
Waitress 1.4.2 ReDoS - CVE-2020-5236 (Blog Sample Code)
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2020-5236 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2020-5236 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
Initial Analysis by [email protected]
Feb. 06, 2020
Action Type Old Value New Value Added CVSS V2 NIST (AV:N/AC:L/Au:S/C:N/I:N/A:C) Added CVSS V3.1 NIST AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Changed Reference Type https://github.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1f No Types Assigned https://github.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1f Patch, Third Party Advisory Changed Reference Type https://github.com/Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgc No Types Assigned https://github.com/Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgc Third Party Advisory Added CWE NIST CWE-400 Added CPE Configuration OR *cpe:2.3:a:agendaless:waitress:1.4.2:*:*:*:*:*:*:* -
CVE Modified by [email protected]
Feb. 04, 2020
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.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2020-5236 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2020-5236
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.08 }} 0.00%
score
0.30714
percentile