---
id: CVE-2025-23217
aliases:
  - GHSA-wg33-5h85-7q5p
  - PYSEC-2026-1630
title: Mitmweb API Authentication Bypass Using Proxy Server
summary: Mitmweb API Authentication Bypass Using Proxy Server
severity: high
vendor: mitmproxy
product: mitmproxy
ecosystem: pip
affected:
  - mitmproxy < 11.1.2
patched:
  - mitmproxy 11.1.2
published: '2025-02-06'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:06.196677106Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-wg33-5h85-7q5p'
references:
  - url: >-
      https://github.com/mitmproxy/mitmproxy/security/advisories/GHSA-wg33-5h85-7q5p
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-23217'
  - url: >-
      https://github.com/mitmproxy/mitmproxy/commit/fa89055e196d953f11fd241e36ee37858993486a
  - url: 'https://en.wikipedia.org/wiki/Server-side_request_forgery'
  - url: 'https://github.com/mitmproxy/mitmproxy'
  - url: 'https://github.com/mitmproxy/mitmproxy/blob/main/CHANGELOG.md'
  - url: >-
      https://github.com/mitmproxy/mitmproxy/blob/main/CHANGELOG.md#06-february-2025-mitmproxy-1112
tags:
  - osv
  - pip
epss: 0.00831
epssPercentile: 0.5607
ingestedAt: '2026-07-08T18:25:53.626Z'
---

## Overview

### Impact
In mitmweb 11.1.0 and below, a malicious client can use mitmweb's proxy server (bound to `*:8080` by default) to access mitmweb's internal API (bound to `127.0.0.1:8081` by default). In other words, while the client cannot access the API directly (good), they can access the API through the proxy (bad). An attacker may be able to escalate this [SSRF](https://en.wikipedia.org/wiki/Server-side_request_forgery)-style access to remote code execution.

The mitmproxy and mitmdump tools are unaffected. Only mitmweb is affected. The `block_global` option, which is enabled by default, blocks connections originating from publicly-routable IP addresses in the proxy. The attacker needs to be in the same local network.

### Patches

The vulnerability has been fixed in mitmproxy 11.1.2 and above.

### Acknowledgements

We thank Stefan Grönke (@gronke) for reporting this vulnerability as part of a security audit by [Radically Open Security](https://www.radicallyopensecurity.com/). This audit was supported by the [NGI0 Entrust fund](https://nlnet.nl/entrust/) established by [NLnet](https://nlnet.nl/).

### Timeline

- **2025-01-14**: Received initial report. 
- **2025-01-14**: Verified report and confirmed receipt.
- **2025-01-19**: Shared patch with researcher.
- **2025-02-04**: Received final confirmation that patch is working.
- **2025-02-05**: Published patched release and advisory.

## Affected packages

- `mitmproxy < 11.1.2`

## Remediation

Upgrade to a patched release:

- `mitmproxy 11.1.2`