6.8

CVE-2020-5236: agendaless waitress Uncontrolled Resource Consumption

CVSS: 6.8v2.0MediumModified
AliasesGHSA-73m2-3pwg-5fgcPYSEC-2020-155
Published 04-02-2020Last modified 04-08-2024
Open JSON

Vulnerability summary

CVE-2020-5236 is a medium (CVSS 6.8) Uncontrolled Resource Consumption vulnerability in agendaless waitress. EPSS estimates a 2.36% chance of exploitation in the next 30 days, higher than 83.6% of scored vulnerabilities.

Overall risk
28/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.8/10
010
Medium · v2.0 (NVD)
EPSS score
2.36%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 04-02-2020
    PublishedVulnerability first disclosed.
  2. 04-08-2024
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 3 sources · 3 versions

EPSS trend

Probability

2.36%

Chance of exploitation in the next 30 days

Percentile

84%

Versus all other CVEs

30-day change

0.00 pp

From 2.36% on 21-09-2026

21-09-202621-10-2026
EPSS score
2.36%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Agendaless1 product
Pylons1 product
PyPI1 product
  • waitress≥ 1.4.2, < 1.4.3 | < 6e46f9e3f014d64dd7d1e258eaf626e39870ee1f | < 1.4.3

3 vendors · 3 products

References

5 links