CVE-2024-37891

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.

Read the notes from the security team

Why is this CVE low priority?

Per urllib3 developers, this is a highly unlikely scenario

Learn more about Ubuntu priority

Status

Show unmaintained releases

Package	Ubuntu Release	Status
python-pip	24.10 oracular	Fixed 24.2+dfsg-1ubuntu0.1
	24.04 LTS noble	Fixed 24.0+dfsg-1ubuntu1.1
	23.10 mantic	Ignored end of life, was needs-triage
	22.04 LTS jammy	Fixed 22.0.2+dfsg-1ubuntu0.5
	20.04 LTS focal	Fixed 20.0.2-5ubuntu1.11
	18.04 LTS bionic	Fixed 9.0.1-2.3~ubuntu1.18.04.8+esm6 Ubuntu Pro
	16.04 LTS xenial	Fixed 8.1.1-2ubuntu0.6+esm10 Ubuntu Pro
	14.04 LTS trusty	Needs evaluation
python-urllib3	24.10 oracular	Fixed 2.0.7-2ubuntu0.1
	24.04 LTS noble	Fixed 2.0.7-1ubuntu0.1
	23.10 mantic	Ignored end of life, was needs-triage
	22.04 LTS jammy	Fixed 1.26.5-1~exp1ubuntu0.2
	20.04 LTS focal	Fixed 1.25.8-2ubuntu0.4
	18.04 LTS bionic	Fixed 1.22-1ubuntu0.18.04.2+esm2 Ubuntu Pro
	16.04 LTS xenial	Fixed 1.13.1-2ubuntu0.16.04.4+esm2 Ubuntu Pro
	14.04 LTS trusty	Needs evaluation

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Notes

mdeslaur

On focal and earlier, the python-pip package bundles python-urllib3 binaries when built. After updating python-urllib3, a no-change rebuild of python-pip is required. On jammy and later, python-urllib3 is bundled in the python-pip package and needs to be patched.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
python-pip	Upstream: 126be63
python-urllib3	Upstream: accff72 Upstream: 40b6d16