medium
4.4
CWE
669
Advisory Published
Advisory Published
Advisory Published
Updated

CVE-2024-37891: Proxy-Authorization request header isn't stripped during cross-origin redirects in urllib3

First published: Mon Jun 17 2024(Updated: )

urllib3 is a user-friendly HTTP client library for Python. When using urllib3's proxy support with `ProxyManager`, the `Proxy-Authorization` header is only sent to the configured proxy, as expected. However, when sending HTTP requests *without* using urllib3's proxy support, it's possible to accidentally configure the `Proxy-Authorization` header even though it won't have any effect as the request is not using a forwarding proxy or a tunneling proxy. In those cases, urllib3 doesn't treat the `Proxy-Authorization` HTTP header as one carrying authentication material and thus doesn't strip the header on cross-origin redirects. Because this is a highly unlikely scenario, we believe the severity of this vulnerability is low for almost all users. Out of an abundance of caution urllib3 will automatically strip the `Proxy-Authorization` header during cross-origin redirects to avoid the small chance that users are doing this on accident. Users should use urllib3's proxy support or disable automatic redirects to achieve safe processing of the `Proxy-Authorization` header, but we still decided to strip the header by default in order to further protect users who aren't using the correct approach. We believe the number of usages affected by this advisory is low. It requires all of the following to be true to be exploited: 1. Setting the `Proxy-Authorization` header without using urllib3's built-in proxy support. 2. Not disabling HTTP redirects. 3. Either not using an HTTPS origin server or for the proxy or target origin to redirect to a malicious origin. Users are advised to update to either version 1.26.19 or version 2.2.2. Users unable to upgrade may use the `Proxy-Authorization` header with urllib3's `ProxyManager`, disable HTTP redirects using `redirects=False` when sending requests, or not user the `Proxy-Authorization` header as mitigations.

Credit: security-advisories@github.com security-advisories@github.com

Affected SoftwareAffected VersionHow to fix
redhat/urllib3<1.26.19
1.26.19
redhat/urllib3<2.2.2
2.2.2
pip/urllib3>=2.0.0<2.2.2
2.2.2
pip/urllib3<1.26.19
1.26.19
F5 BIG-IP>=17.1.0<=17.1.1
F5 BIG-IP>=16.1.0<=16.1.5
F5 BIG-IP>=15.1.0<=15.1.10
F5 BIG-IQ Centralized Management>=8.2.0<=8.3.0
F5 F5OS-A=1.7.0>=1.5.1<=1.5.2
F5 F5OS-C>=1.6.0<=1.6.2
debian/python-urllib3<=1.26.5-1~exp1
1.26.5-1~exp1+deb11u1
1.26.12-1+deb12u1
2.3.0-1
IBM QRadar SIEM<=7.5 - 7.5.0 UP9 IF03
IBM QRadar Incident Forensics<=7.5 - 7.5.0 UP9 IF03

Never miss a vulnerability like this again

Sign up to SecAlerts for real-time vulnerability data matched to your software, aggregated from hundreds of sources.

Read MoreStart Free Trial

Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Frequently Asked Questions

  • What is the severity of CVE-2024-37891?

    CVE-2024-37891 has been classified as a medium severity vulnerability.

  • How do I fix CVE-2024-37891?

    To fix CVE-2024-37891, upgrade urllib3 to version 1.26.19 or 2.2.2.

  • What does CVE-2024-37891 affect?

    CVE-2024-37891 affects the urllib3 HTTP client library used in various packages and products.

  • Can CVE-2024-37891 be exploited?

    Yes, CVE-2024-37891 can be exploited by attackers to compromise the confidentiality of the proxy authorization headers.

  • Which versions of urllib3 are vulnerable to CVE-2024-37891?

    Versions of urllib3 prior to 1.26.19 and 2.2.2 are vulnerable to CVE-2024-37891.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2025 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203