CVE-2016-6580: Python Priority Library

High severity, CVSS 7.5. EPSS: 1.8% chance of exploitation in the next 30 days.

A HTTP/2 implementation built using any version of the Python priority library prior to version 1.2.0 could be targeted by a malicious peer by having that peer assign priority information for every possible HTTP/2 stream ID. The priority tree would happily continue to store the priority information for each stream, and would therefore allocate unbounded amounts of memory. Attempting to actually use a tree like this would also cause extremely high CPU usage to maintain the tree.

Affected products

• Python Python Priority Library: version 1.0.0 only; version 1.1.0 only; version 1.1.1 only

Published 2017-01-10. Last modified 2026-06-17.