CVE-2025-23389: Improper Access Control Vulnerability in SUSE Rancher

Overview

We are highlighting a significant cybersecurity vulnerability identified as CVE-2025-23389. This vulnerability is an Improper Access Control issue that affects the SUSE Rancher. This software flaw allows a local user to impersonate other identities through the SAML Authentication process upon their first login. The affected users could be anyone using the vulnerable versions of the SUSE Rancher software, and the impact is substantial as it could potentially lead to system compromise or data leakage. Considering the high severity of this vulnerability, immediate action is necessary to prevent potential cyber threats.

Vulnerability Summary

CVE ID: CVE-2025-23389
Severity: High (8.4 CVSS score)
Attack Vector: Local
Privileges Required: Low
User Interaction: Required
Impact: System compromise, potential data leakage

Affected Products

Product | Affected Versions

Rancher | 2.8.0 – 2.8.13
Rancher | 2.9.0 – 2.9.7
Rancher | 2.10.0 – 2.10.3

How the Exploit Works

The exploit leverages an Improper Access Control vulnerability in the SUSE Rancher. Specifically, this flaw arises from the software failing to correctly validate user identities during the SAML Authentication process. As a result, an attacker with local access to the system can exploit this vulnerability to impersonate other users on their first login. This can potentially provide unauthorized access to sensitive data or even system-level controls.

Conceptual Example Code

While we cannot provide a real example of the exploit to avoid misuse, we can illustrate a conceptual example of how this exploit might work. The attacker could potentially manipulate the SAML response data to impersonate another user. The following is a conceptual example:

POST /saml/SSO/alias/rancher HTTP/1.1
Host: target.example.com
Content-Type: application/xml
<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol"
ID="identifier_1"
Version="2.0"
IssueInstant="2025-01-01T00:00:00Z"
Destination="http://www.example.com/SSOService.aspx"
InResponseTo="identifier_2">
<saml:Issuer xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">
http://www.example.com
</saml:Issuer>
<saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
ID="identifier_3"
IssueInstant="2025-01-01T00:00:00Z"
Version="2.0">
<saml:Subject>
<saml:NameID>@NotTheRealUser</saml:NameID>
</saml:Subject>
</saml:Assertion>
</samlp:Response>

In this mock-up, the attacker changes the ‘NameID’ field to the victim’s username, thus pretending to be them during the authentication process.

Recommendations for Mitigation

To mitigate this vulnerability, users are advised to apply the vendor patch as soon as possible. For temporary mitigation, users can employ Web Application Firewalls (WAFs) or Intrusion Detection Systems (IDSs) to monitor and control SAML traffic on their network.