CVE-2025-23217: Mitmproxy Authentication Bypass Vulnerability

HIGH
Advisory Identifier: GHSA-wg33-5h85-7q5p
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CWE-441 CWE-288
Published
Advisory Summary

CVE-2025-23217 is a HIGH authentication bypass vulnerability (CWE-441: Unintended Proxy or Intermediary ('Confused Deputy')) affecting Mitmproxy libraries in the PyPI ecosystem. The issue involves mitmweb api authentication bypass using proxy server. Remediation is available by upgrading affected packages to version 11.1.2.

CVE-2025-23217 at a Glance

CVE Identifier CVE-2025-23217
GHSA Identifier GHSA-wg33-5h85-7q5p
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-441: Unintended Proxy or Intermediary ('Confused Deputy')
Affected Product Mitmproxy
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix CVE-2025-23217

To remediate this vulnerability, upgrade all affected Mitmproxy dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

mitmproxy fixed: 11.1.2 
pip install mitmproxy>=11.1.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show mitmproxy

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2025-23217, inspect your installed packages using pip:

pip show mitmproxy

Analyze the terminal output to locate any version of Mitmproxy in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 11.1.2), your application is affected.

Note: The pip show mitmproxy command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-441: Unintended Proxy or Intermediary ('Confused Deputy'), where the product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. this causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor. In Mitmproxy, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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.

CVE-2025-23217 Affected Mitmproxy Versions

1 component(s)
Fixed Versions:
11.1.2
Product / Package Ecosystem Affected Versions Fixed Version
mitmproxy
pypi/mitmproxy
PyPI
< 11.1.2
11.1.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/mitmproxy/mitmproxy/security/advisories/GHSA-wg33-5h85-7q5p
NVD — CVE-2025-23217 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-23217
Security Fix Commit FIX COMMIT
https://github.com/mitmproxy/mitmproxy/commit/fa89055e196d953f11fd241e36ee37858993486a
en.wikipedia.org/wiki/server-side_re... WEB
https://en.wikipedia.org/wiki/Server-side_request_forgery
Mitmproxy Source Repository REPOSITORY
https://github.com/mitmproxy/mitmproxy
Mitmproxy Source Repository REPOSITORY
https://github.com/mitmproxy/mitmproxy/blob/main/CHANGELOG.md
Mitmproxy Source Repository REPOSITORY
https://github.com/mitmproxy/mitmproxy/blob/main/CHANGELOG.md#06-february-2025-mitmproxy-1112

Frequently Asked Questions

What is CVE-2025-23217?
CVE-2025-23217 is a security vulnerability in Mitmproxy involving Mitmweb API Authentication Bypass Using Proxy Server under CWE-441: Unintended Proxy or Intermediary ('Confused Deputy').
Which Mitmproxy versions are affected?
Affected versions include releases prior to 11.1.2 across affected packages: mitmproxy.
What version fixes CVE-2025-23217?
Upgrading to 11.1.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is mitmproxy affected?
Yes, mitmproxy is affected in releases prior to 11.1.2. Upgrade your dependency to 11.1.2 or later.
What CWE is associated with CVE-2025-23217?
CVE-2025-23217 is classified under CWE-441: Unintended Proxy or Intermediary ('Confused Deputy') (The product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. This causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor.).
How can I check PyPI dependencies for CVE-2025-23217?
Run the dependency tree command: 'pip show mitmproxy'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wg33-5h85-7q5p",
  "modified" : "2025-02-06T19:54:56Z",
  "published" : "2025-02-06T17:07:41Z",
  "aliases" : [ "CVE-2025-23217" ],
  "summary" : "Mitmweb API Authentication Bypass Using Proxy Server",
  "details" : "### Impact\nIn 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.\n\nThe 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.\n\n### Patches\n\nThe vulnerability has been fixed in mitmproxy 11.1.2 and above.\n\n### Acknowledgements\n\nWe 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/).\n\n### Timeline\n\n- **2025-01-14**: Received initial report. \n- **2025-01-14**: Verified report and confirmed receipt.\n- **2025-01-19**: Shared patch with researcher.\n- **2025-02-04**: Received final confirmation that patch is working.\n- **2025-02-05**: Published patched release and advisory.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "mitmproxy"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "11.1.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/mitmproxy/mitmproxy/security/advisories/GHSA-wg33-5h85-7q5p"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-23217"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mitmproxy/mitmproxy/commit/fa89055e196d953f11fd241e36ee37858993486a"
  }, {
    "type" : "WEB",
    "url" : "https://en.wikipedia.org/wiki/Server-side_request_forgery"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mitmproxy/mitmproxy"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mitmproxy/mitmproxy/blob/main/CHANGELOG.md"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mitmproxy/mitmproxy/blob/main/CHANGELOG.md#06-february-2025-mitmproxy-1112"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-288", "CWE-441" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-02-06T17:07:41Z",
    "nvd_published_at" : "2025-02-06T18:15:32Z"
  }
}