Resource Exhaustion The advisory has been revoked - it doesn't affect any version of package python-waitress.src (opens in a new tab)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-RHEL10-PYTHONWAITRESSSRC-12614555
- published11 Sept 2025
- disclosed3 Feb 2020
Introduced: 3 Feb 2020
CVE-2020-5236 (opens in a new tab)Amendment
The Red Hat security team deemed this advisory irrelevant for RHEL:10.
NVD Description
Note: Versions mentioned in the description apply only to the upstream python-waitress.src package and not the python-waitress.src package as distributed by RHEL.
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.