6.8
MEDIUM CVSS 2.0
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 :

Nov. 21, 2024, 5:33 a.m.

Remotely Exploit :

Yes !
Affected Products

The following products are affected by CVE-2020-5236 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Agendaless waitress
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 2.0 MEDIUM [email protected]
CVSS 3.1 MEDIUM [email protected]
CVSS 3.1 MEDIUM [email protected]
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
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
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.

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

Updated: 1 week, 2 days ago
0 stars 0 fork 0 watcher
Born at : May 8, 2023, 12:28 p.m. This repo has been linked 9 different CVEs too.

Fetches security vulnerabilities and creates pip-constraints based on them.

python security dependencies pip supply-chain-security

Python Shell

Updated: 2 months, 3 weeks ago
12 stars 1 fork 1 watcher
Born at : Nov. 4, 2022, 2:14 p.m. This repo has been linked 3 different CVEs too.

None

Updated: 4 months, 3 weeks ago
9 stars 1 fork 1 watcher
Born at : June 21, 2022, 7:45 a.m. This repo has been linked 944 different CVEs too.

List of RegEx DoS (ReDoS) CVEs and resources

security awesome redos regex dos regex-dos pentesting awesome-list regex-security

Updated: 6 months ago
27 stars 3 fork 3 watcher
Born at : June 10, 2021, 1:57 a.m. This repo has been linked 76 different CVEs too.

None

Updated: 4 months, 3 weeks ago
18 stars 10 fork 10 watcher
Born at : Jan. 2, 2021, 10:19 p.m. This repo has been linked 1053 different CVEs too.

None

Updated: 2 months ago
84 stars 31 fork 31 watcher
Born at : Oct. 2, 2020, 2:49 p.m. This repo has been linked 1114 different CVEs too.

Waitress 1.4.2 ReDoS - CVE-2020-5236 (Blog Sample Code)

Python

Updated: 1 year ago
4 stars 0 fork 0 watcher
Born at : Feb. 6, 2020, 6:21 a.m. This repo has been linked 1 different CVEs too.

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 af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference https://github.com/Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1f
    Added Reference https://github.com/Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgc
  • 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.
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 6.5
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact
Base CVSS Score: 6.8
Access Vector
Access Complexity
Authentication
Confidentiality Impact
Integrity Impact
Availability Impact
Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

15.50 }} 1.57%

score

0.94249

percentile