urllib3 redirects are not disabled when retries are disabled on PoolManager instantiation
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)
# 302However, 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 thePoolManager()level.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | urllib3 | < 2.5.0 | 2.5.0 |
References
- https://github.com/urllib3/urllib3/security/advisories/GHSA-pq67-6m6q-mj2v
- https://nvd.nist.gov/vuln/detail/CVE-2025-50181
- https://github.com/urllib3/urllib3/commit/f05b1329126d5be6de501f9d1e3e36738bc08857
- https://github.com/urllib3/urllib3
- https://github.com/urllib3/urllib3/releases/tag/2.5.0
- https://pypi.org/project/urllib3
- https://github.com/advisories/GHSA-pq67-6m6q-mj2v
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N- Weakness (CWE)
CWE-601- Platform
- Python (PyPI)
- Package
urllib3- Disclosed
- 18.06.2025
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-1999 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-pq67-6m6q-mj2v - CC BY 4.0
Vulnerability history: urllib3
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 22
- First → latest
- 01.2017 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 11
- Medium 10
Disclosures per year
- 2017: 1
- 2018: 1
- 2019: 2
- 2020: 2
- 2021: 2
- 2022: 0
- 2023: 3
- 2024: 1
- 2025: 4
- 2026: 6
-
urllib3 redirects are not disabled when retries are disabled on PoolManager instantiation this entry
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