What’s Vulnerable › Vulnerabilities

CVE-2024-49769: Waitress has a denial of service leading to high CPU usage/resource exhaustion

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-10-29 · updated 2026-06-17
• Weakness: CWE-772

Description

Waitress is a Web Server Gateway Interface server for Python 2 and 3. When a remote client closes the connection before waitress has had the opportunity to call getpeername() waitress won't correctly clean up the connection leading to the main thread attempting to write to a socket that no longer exists, but not removing it from the list of sockets to attempt to process. This leads to a busy-loop calling the write function. A remote attacker could run waitress out of available sockets with very little resources required. Waitress 3.0.1 contains fixes that remove the race condition.

Affected products

• Pylons Waitress: before 3.0.1 — fixed in 3.0.1

How to fix

Upgrade to a fixed version: Pylons Waitress 3.0.1. Check the vendor advisory for mitigations.

References

• https://github.com/Pylons/waitress/commit/1ae4e894c9f76543bee06584001583fc6fa8c95c
• https://github.com/Pylons/waitress/issues/418
• https://github.com/Pylons/waitress/pull/435
• https://github.com/Pylons/waitress/security/advisories/GHSA-3f84-rpwh-47g6
• https://lists.debian.org/debian-lts-announce/2024/11/msg00012.html

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