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.
Affected usages
We believe the number of usages affected by this advisory is low. It requires all of the following to be true to be exploited:
Setting the Proxy-Authorization header without using urllib3's built-in proxy support.
Not disabling HTTP redirects.
Either not using an HTTPS origin server or for the proxy or target origin to redirect to a malicious origin.
Remediation
Using the Proxy-Authorization header with urllib3's ProxyManager.
Disabling HTTP redirects using redirects=False when sending requests.
This PR contains the following updates:
==1.26.18->==1.26.19GitHub Vulnerability Alerts
CVE-2024-37891
When using urllib3's proxy support with
ProxyManager, theProxy-Authorizationheader 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-Authorizationheader 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 theProxy-AuthorizationHTTP 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-Authorizationheader 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-Authorizationheader, but we still decided to strip the header by default in order to further protect users who aren't using the correct approach.Affected usages
We believe the number of usages affected by this advisory is low. It requires all of the following to be true to be exploited:
Proxy-Authorizationheader without using urllib3's built-in proxy support.Remediation
Proxy-Authorizationheader with urllib3'sProxyManager.redirects=Falsewhen sending requests.Proxy-Authorizationheader.Release Notes
urllib3/urllib3 (urllib3)
### [`v1.26.19`](https://togithub.com/urllib3/urllib3/compare/1.26.18...1.26.19) [Compare Source](https://togithub.com/urllib3/urllib3/compare/1.26.18...1.26.19)Configuration
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