CVE-2024-37891 Information

Description

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.

Reference

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

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.