Advisory Severity Curation

`Cookie` HTTP header isn't stripped on cross-origin redirects urllib3 doesn't treat the `Cookie` HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a `Cookie` header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly. Users **must** handle redirects themselves instead of relying on urllib3's automatic redirects to achieve safe processing of the `Cookie` header, thus we 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: * Using an affected version of urllib3 (patched in v1.26.17 and v2.0.6) * Using the `Cookie` header on requests, which is mostly typical for impersonating a browser. * Not disabling HTTP redirects * Either not using HTTPS or for the origin server to redirect to a malicious origin. ## Remediation * Upgrading to at least urllib3 v1.26.17 or v2.0.6 * Disabling HTTP redirects using `redirects=False` when sending requests. * Not using the `Cookie` header.

`Cookie` HTTP header isn't stripped on cross-origin redirects urllib3 doesn't treat the `Cookie` HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a `Cookie` header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly. Users **must** handle redirects themselves instead of relying on urllib3's automatic redirects to achieve safe processing of the `Cookie` header, thus we decided to strip the header by default in order to further protect users who aren't using the correct approach.

urllib3 is a user-friendly HTTP client library for Python. urllib3 doesn't treat the `Cookie` HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a `Cookie` header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly. This issue has been patched in urllib3 version 1.26.17 or 2.0.5.

urllib3 is a user-friendly HTTP client library for Python. urllib3 doesn't treat the `Cookie` HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a `Cookie` header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly. This issue has been patched in urllib3 version 1.26.17 or 2.0.5.