What’s Vulnerable › Vulnerabilities

CVE-2021-3116

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-01-11 · updated 2026-06-17
• Weakness: CWE-697

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).

Affected products

• Proxy.Py Project Proxy.Py: before 2.3.1 — fixed in 2.3.1

How to fix

Upgrade to a fixed version: Proxy.Py Project Proxy.Py 2.3.1. Check the vendor advisory for mitigations.

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
• 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

Get alerted when CVE-2021-3116 or the next vulnerability affects your stack