Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2020-5236

18
FAUCET Score

CVE-2020-5236 describes a Denial of Service (DoS) vulnerability in Waitress version 1.4.2, affecting the agendaless waitress product. An attacker can exploit this by sending a single HTTP request with a malformed header containing invalid characters, causing the regular expression engine to catastrophically backtrack and consume 100% CPU, effectively taking the service offline. This vulnerability has a CVSS score of 6.5 (Medium) due to its network-based attack vector and high availability impact, though it requires low privileges and complexity. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
1.4.2CPE matchmatch criteria
cpe:2.3:a:agendaless:waitress:1.4.2:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.7MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.1
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.64%
Probability of exploitation in next 30 days
EPSS Percentile
84.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0264 is in the 94th percentile among its peer group of 21,958 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: waitressFixed in: 1.4.3
redhatvendor investigatingvia redhat_api
Product: Red Hat OpenStack Platform 16 (Train)Fixed in: python-waitress

Vendor Advisories (2)

pipGHSA-73m2-3pwg-5fgcmedium

Catastrophic backtracking in regex allows Denial of Service in Waitress

Feb 4, 2020
redhatCVE-2020-5236Moderate

waitress: header with invalid characters can lead to DoS

Feb 3, 2020

References

github.com / Pylons/waitress/commit/6e46f9e3f014d64dd7d1e258eaf626e39870ee1f
PatchThird Party Advisory
github.com / Pylons/waitress/security/advisories/GHSA-73m2-3pwg-5fgc
Third Party Advisory