CVE-2025-51471 is a vulnerability identified in Ollama version 0.6.7 involving a cross-domain token exposure issue within the server.auth.getAuthorizationToken function. The vulnerability arises due to improper handling of the WWW-Authenticate header returned by the /api/pull endpoint. Specifically, a malicious actor can manipulate the 'realm' value in this header to trick the system into exposing authentication tokens across domain boundaries. This exposure allows remote attackers to steal authentication tokens, which can then be used to bypass access controls and gain unauthorized access to protected resources or services. The flaw is rooted in the failure to properly validate or sanitize the realm parameter, enabling cross-domain token leakage. Although no known exploits are currently reported in the wild, the vulnerability poses a significant risk because authentication tokens are critical for maintaining session integrity and access control. The lack of a CVSS score indicates that the vulnerability is newly published and not yet fully assessed for severity by standard frameworks. The affected versions are not explicitly listed beyond 0.6.7, but it is implied that this version is vulnerable. The vulnerability impacts the confidentiality and integrity of authentication tokens and potentially the availability of services if unauthorized access leads to disruption.

For European organizations, this vulnerability could have serious consequences, especially for those relying on Ollama 0.6.7 or similar affected versions in their infrastructure. The theft of authentication tokens can lead to unauthorized access to sensitive data, internal systems, or cloud services, resulting in data breaches, intellectual property theft, or disruption of business operations. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the sensitive nature of their data and regulatory requirements like GDPR. The cross-domain nature of the token exposure increases the risk of attacks originating from compromised or malicious third-party domains, complicating detection and response efforts. Additionally, the ability to bypass access controls undermines trust in authentication mechanisms and may facilitate lateral movement within networks. The absence of known exploits currently provides a window for proactive mitigation, but the potential impact remains high if exploited.

To mitigate this vulnerability, European organizations should first verify if they are using Ollama version 0.6.7 or any other affected versions. Immediate steps include: 1) Applying any available patches or updates from the vendor once released. 2) Implementing strict validation and sanitization of the 'realm' parameter in the WWW-Authenticate header at the application or API gateway level to prevent malicious manipulation. 3) Employing web application firewalls (WAFs) configured to detect and block anomalous or suspicious header values that could indicate exploitation attempts. 4) Monitoring authentication token usage and access logs for unusual patterns that may suggest token theft or misuse. 5) Enforcing short token lifetimes and using refresh tokens with secure storage to limit the window of opportunity for attackers. 6) Conducting security assessments and penetration testing focused on authentication flows and cross-domain interactions. 7) Educating developers and security teams about secure token handling and cross-origin resource sharing (CORS) policies to prevent similar vulnerabilities. These measures go beyond generic advice by focusing on the specific attack vector and token management practices relevant to this vulnerability.