Security Tracking Issue

Do not make this issue public.

Impact: Moderate
Reported Date: 17-Jun-2024
Resolve Bug By: 15-Sep-2024

In case the dates above are already past, please evaluate this bug in your next prioritization review and make a decision then. Remember to explicitly set CLOSED:WONTFIX (in Bugzilla) or Closed:Won't Do (in Jira) if you decide not to fix this bug.

Please review this tracker and its impact on your product or service, as soon as possible. The trackers are filed WITHOUT in-depth analysis as the vulnerability has a Low or Moderate severity impact on this product or service. For more details, please refer to following confluence page - https://docs.engineering.redhat.com/x/3e_3EQ

Please see the Security Errata Policy for further details: https://docs.engineering.redhat.com/x/9kKpDw

Flaw:

CVE-2024-37891 urllib3: proxy-authorization request header is not stripped during cross-origin redirects
https://bugzilla.redhat.com/show_bug.cgi?id=2292788

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.

https://github.com/urllib3/urllib3/commit/accff72ecc2f6cf5a76d9570198a93ac7c90270e
https://github.com/urllib3/urllib3/security/advisories/GHSA-34jh-p97f-mpxf