GHSA-PQ67-6M6Q-MJ2V

Vulnerability from github – Published: 2025-06-18 17:50 – Updated: 2025-12-22 21:33
VLAI
Summary
urllib3 redirects are not disabled when retries are disabled on PoolManager instantiation
Details

urllib3 handles redirects and retries using the same mechanism, which is controlled by the Retry object. The most common way to disable redirects is at the request level, as follows:

resp = urllib3.request("GET", "https://httpbin.org/redirect/1", redirect=False)
print(resp.status)
# 302

However, it is also possible to disable redirects, for all requests, by instantiating a PoolManager and specifying retries in a way that disable redirects:

import urllib3

http = urllib3.PoolManager(retries=0)  # should raise MaxRetryError on redirect
http = urllib3.PoolManager(retries=urllib3.Retry(redirect=0))  # equivalent to the above
http = urllib3.PoolManager(retries=False)  # should return the first response

resp = http.request("GET", "https://httpbin.org/redirect/1")

However, the retries parameter is currently ignored, which means all the above examples don't disable redirects.

Affected usages

Passing retries on PoolManager instantiation to disable redirects or restrict their number.

By default, requests and botocore users are not affected.

Impact

Redirects are often used to exploit SSRF vulnerabilities. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable.

Remediation

You can remediate this vulnerability with the following steps:

  • Upgrade to a patched version of urllib3. If your organization would benefit from the continued support of urllib3 1.x, please contact sethmichaellarson@gmail.com to discuss sponsorship or contribution opportunities.
  • Disable redirects at the request() level instead of the PoolManager() level.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "urllib3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.5.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-50181"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-601"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-06-18T17:50:00Z",
    "nvd_published_at": "2025-06-19T01:15:24Z",
    "severity": "MODERATE"
  },
  "details": "urllib3 handles redirects and retries using the same mechanism, which is controlled by the `Retry` object. The most common way to disable redirects is at the request level, as follows:\n\n```python\nresp = urllib3.request(\"GET\", \"https://httpbin.org/redirect/1\", redirect=False)\nprint(resp.status)\n# 302\n```\n\nHowever, it is also possible to disable redirects, for all requests, by instantiating a `PoolManager` and specifying `retries` in a way that disable redirects:\n\n```python\nimport urllib3\n\nhttp = urllib3.PoolManager(retries=0)  # should raise MaxRetryError on redirect\nhttp = urllib3.PoolManager(retries=urllib3.Retry(redirect=0))  # equivalent to the above\nhttp = urllib3.PoolManager(retries=False)  # should return the first response\n\nresp = http.request(\"GET\", \"https://httpbin.org/redirect/1\")\n```\n\nHowever, the `retries` parameter is currently ignored, which means all the above examples don\u0027t disable redirects.\n\n## Affected usages\n\nPassing `retries` on `PoolManager` instantiation to disable redirects or restrict their number.\n\nBy default, requests and botocore users are not affected.\n\n## Impact\n\nRedirects are often used to exploit SSRF vulnerabilities. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable.\n\n## Remediation\n\nYou can remediate this vulnerability with the following steps:\n\n * Upgrade to a patched version of urllib3. If your organization would benefit from the continued support of urllib3 1.x, please contact [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com) to discuss sponsorship or contribution opportunities.\n * Disable redirects at the `request()` level instead of the `PoolManager()` level.",
  "id": "GHSA-pq67-6m6q-mj2v",
  "modified": "2025-12-22T21:33:21Z",
  "published": "2025-06-18T17:50:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-pq67-6m6q-mj2v"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-50181"
    },
    {
      "type": "WEB",
      "url": "https://github.com/urllib3/urllib3/commit/f05b1329126d5be6de501f9d1e3e36738bc08857"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/urllib3/urllib3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/urllib3/urllib3/releases/tag/2.5.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "urllib3 redirects are not disabled when retries are disabled on PoolManager instantiation"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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