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.
urllib3 previously wouldn't remove the HTTP request body when an HTTP redirect response using status 303 "See Other" after the request had its method changed from one that could accept a request body (like POST) to GET as is required by HTTP RFCs. Although the behavior of removing the request body is not specified in the section for redirects, it can be inferred by piecing together information from different sections and we have observed the behavior in other major HTTP client implementations like curl and web browsers.
A client SHOULD NOT generate content in a GET request unless it is made directly to an origin server that has previously indicated, in or out of band, that such a request has a purpose and will be adequately supported.
Affected usages
Because the vulnerability requires a previously trusted service to become compromised in order to have an impact on confidentiality we believe the exploitability of this vulnerability is low. Additionally, many users aren't putting sensitive data in HTTP request bodies, if this is the case then this vulnerability isn't exploitable.
Both of the following conditions must be true to be affected by this vulnerability:
If you're using urllib3 and submitting sensitive information in the HTTP request body (such as form data or JSON)
The origin service is compromised and starts redirecting using 303 to a malicious peer or the redirected-to service becomes compromised.
Remediation
You can remediate this vulnerability with any of the following steps:
Upgrade to a patched version of urllib3 (v1.26.18 or v2.0.7)
Disable redirects for services that you aren't expecting to respond with redirects with redirects=False.
Disable automatic redirects with redirects=False and handle 303 redirects manually by stripping the HTTP request body.
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.
Not using the Proxy-Authorization header.
Release Notes
urllib3/urllib3 (urllib3)
### [`v1.26.19`](https://togithub.com/urllib3/urllib3/blob/HEAD/CHANGES.rst#12619-2024-06-17)
[Compare Source](https://togithub.com/urllib3/urllib3/compare/1.26.18...1.26.19)
\====================
- Added the `Proxy-Authorization` header to the list of headers to strip from requests when redirecting to a different host. As before, different headers can be set via `Retry.remove_headers_on_redirect`.
- Fixed handling of OpenSSL 3.2.0 new error message for misconfiguring an HTTP proxy as HTTPS. (`#3405 `\__)
### [`v1.26.18`](https://togithub.com/urllib3/urllib3/blob/HEAD/CHANGES.rst#12618-2023-10-17)
[Compare Source](https://togithub.com/urllib3/urllib3/compare/1.26.17...1.26.18)
\====================
- Made body stripped from HTTP requests changing the request method to GET after HTTP 303 "See Other" redirect responses.
### [`v1.26.17`](https://togithub.com/urllib3/urllib3/blob/HEAD/CHANGES.rst#12617-2023-10-02)
[Compare Source](https://togithub.com/urllib3/urllib3/compare/1.26.16...1.26.17)
\====================
- Added the `Cookie` header to the list of headers to strip from requests when redirecting to a different host. As before, different headers can be set via `Retry.remove_headers_on_redirect`. (`#3139 `\_)
Configuration
📅 Schedule: Branch creation - "" in timezone Etc/UTC, Automerge - At any time (no schedule defined).
🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.
♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
🔕 Ignore: Close this PR and you won't be reminded about this update again.
[ ] If you want to rebase/retry this PR, check this box
This PR contains the following updates:
1.26.16->1.26.19GitHub Vulnerability Alerts
CVE-2023-43804
urllib3 doesn't treat the
CookieHTTP 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 aCookieheader 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
Cookieheader, 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:
Cookieheader on requests, which is mostly typical for impersonating a browser.Remediation
redirects=Falsewhen sending requests.Cookieheader.CVE-2023-45803
urllib3 previously wouldn't remove the HTTP request body when an HTTP redirect response using status 303 "See Other" after the request had its method changed from one that could accept a request body (like
POST) toGETas is required by HTTP RFCs. Although the behavior of removing the request body is not specified in the section for redirects, it can be inferred by piecing together information from different sections and we have observed the behavior in other major HTTP client implementations like curl and web browsers.From RFC 9110 Section 9.3.1:
Affected usages
Because the vulnerability requires a previously trusted service to become compromised in order to have an impact on confidentiality we believe the exploitability of this vulnerability is low. Additionally, many users aren't putting sensitive data in HTTP request bodies, if this is the case then this vulnerability isn't exploitable.
Both of the following conditions must be true to be affected by this vulnerability:
Remediation
You can remediate this vulnerability with any of the following steps:
redirects=False.redirects=Falseand handle 303 redirects manually by stripping the HTTP request body.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/blob/HEAD/CHANGES.rst#12619-2024-06-17) [Compare Source](https://togithub.com/urllib3/urllib3/compare/1.26.18...1.26.19) \==================== - Added the `Proxy-Authorization` header to the list of headers to strip from requests when redirecting to a different host. As before, different headers can be set via `Retry.remove_headers_on_redirect`. - Fixed handling of OpenSSL 3.2.0 new error message for misconfiguring an HTTP proxy as HTTPS. (`#3405Configuration
📅 Schedule: Branch creation - "" in timezone Etc/UTC, Automerge - At any time (no schedule defined).
🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.
♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
🔕 Ignore: Close this PR and you won't be reminded about this update again.
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