# CVE-2018-25091: Authorization Header forwarded on redirect

Source: https://junglewise.ai/threats/cve-2018-25091-authorization-header-forwarded-on-redirect  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2023-10-15  
License: CC BY 4.0 with a link back

CVE-2018-25091 · Severity: low · CVSS 3.1 · Published 2023-10-15

urllib3 before 1.24.2 does not remove the authorization HTTP header when following a cross-origin redirect (i.e., a redirect that differs in host, port, or scheme). This can allow for credentials in the authorization header to be exposed to unintended hosts or transmitted in cleartext. NOTE: this issue exists because of an incomplete fix for CVE-2018-20060 (which was case-sensitive).

Technologies: [urllib3 (PyPI)](https://junglewise.ai/threats/technologies/urllib3). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2018-25091 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2018-25091 being exploited in the wild.

**How severe is CVE-2018-25091?** Low severity, with a CVSS score of 3.1, published 15 October 2023.

**Which products and versions are affected?** urllib3 (PyPI) ECOSYSTEM:introduced=0,fixed=1.24.2, GIT:introduced=0,fixed=adb358f8e06865406d1f05e581a16cbea2136fbc|ECOSYSTEM:introduced=0,fixed=1.24.2.

**Is there a fix for CVE-2018-25091?** Yes. urllib3 (PyPI): upgrade to 1.24.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2018-25091?** Check whether you run urllib3 (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- urllib3 (PyPI): upgrade to 1.24.2 or later

  ```sh
  pip install "urllib3>=1.24.2"
  ```


## Affected products

- urllib3 (PyPI) ECOSYSTEM:introduced=0,fixed=1.24.2, GIT:introduced=0,fixed=adb358f8e06865406d1f05e581a16cbea2136fbc|ECOSYSTEM:introduced=0,fixed=1.24.2

## Identifiers

- CVE-2018-25091
- GHSA-gwvm-45gx-3cf8
- PYSEC-2023-207

## Related threats

- [urllib3 HTTP client unbounded memory allocation in chunked transfer](https://junglewise.ai/threats/cve-2026-97689-urllib3-is-an-http-client-library-for-python-from-1-10-3-until-2)
- [urllib3 infinite loop in Deflate decoder](https://junglewise.ai/threats/cve-2026-97688-urllib3-is-an-http-client-library-for-python-from-2-6-2-until-2-8)
- [urllib3 HTTPS proxy TLS settings isolation](https://junglewise.ai/threats/cve-2026-97687-urllib3-is-an-http-client-library-for-python-from-1-26-0-until-2)
- [PYSEC-2026-1997 - urllib3 does not control redirects in browsers and Node.js](https://junglewise.ai/threats/cve-2025-50182-urllib3-does-not-control-redirects-in-browsers-and-node-js)
- [PYSEC-2026-1999 - urllib3 redirects are not disabled when retries are disabled on PoolManager instantiation](https://junglewise.ai/threats/cve-2025-50181-urllib3-redirects-are-not-disabled-when-retries-are-disabled-on)