Rancher API Server Cross-site Scripting Vulnerability

Impact

A vulnerability has been identified in which unauthenticated cross-site scripting (XSS) in the API Server's public API endpoint can be exploited. This can lead to an attacker exploiting the vulnerability to trigger JavaScript code and execute commands remotely.

The attack vector was identified as a Reflected XSS.

API Server propagates malicious payloads from user input to the UI, which renders the output. For example, a malicious URL gets rendered into a script that is executed on a page.

The changes addressed by this fix are:

• Encode input that comes from the request URL before adding it to the response.
• The request input is escaped by changing the URL construction that is used for links to use url.URL.
• The request input is escaped by escaping the JavaScript and CSS variables with attribute encoding as defined by OWASP.

Patches

Patched versions include the following commits:

Branch	Commit
master	4fd7d82
release/v2.8	69b3c2b
release/v2.8.s3	a3b9e37
release/v2.7	4e102cf
release/v2.7.s3	97a10a3
release/v2.6	4df268e

Workarounds

There is no direct mitigation besides updating API Server to a patched version.

References

If you have any questions or comments about this advisory:

• Reach out to the SUSE Rancher Security team for security-related inquiries.
• Open an issue in the Rancher repository.
• Verify with our support matrix and product support lifecycle.