CVE-2025-67485 identifies a protection mechanism failure (CWE-693) in machphy's mad-proxy, a Python-based HTTP/HTTPS proxy server used for detecting and blocking malicious web activity through custom security policies. Versions 0.3 and earlier contain a vulnerability that allows attackers to bypass the proxy's traffic interception rules. This bypass means that HTTP and HTTPS traffic intended to be inspected and filtered by mad-proxy can instead pass through unmonitored, potentially exposing sensitive information such as credentials, session tokens, or confidential data. The vulnerability does not require any authentication or user interaction, and can be exploited remotely over the network (CVSS vector: AV:N/AC:L/PR:N/UI:N). The flaw impacts confidentiality but does not affect integrity or availability. At the time of publication, no patch or fix is available, and no known exploits have been reported in the wild. The vulnerability arises from improper enforcement of security policies within the proxy, allowing certain traffic to circumvent inspection. Organizations relying on mad-proxy for web security monitoring and policy enforcement are at risk of data leakage and reduced visibility into malicious web activity. The medium severity rating (CVSS 5.3) reflects the moderate impact and ease of exploitation without privileges or interaction. This vulnerability highlights the importance of robust proxy security mechanisms and timely patching in security infrastructure components.

For European organizations, the primary impact of CVE-2025-67485 is the potential exposure of sensitive web traffic that bypasses inspection by mad-proxy. This can lead to leakage of confidential information, including personal data protected under GDPR, corporate credentials, and other sensitive communications. Organizations in finance, healthcare, government, and critical infrastructure sectors are particularly vulnerable due to the sensitivity of their data and regulatory requirements. The inability to intercept and block malicious web activity reduces overall network security posture, increasing the risk of further exploitation by attackers leveraging unmonitored traffic. Since mad-proxy is used to enforce custom security policies, bypassing these controls undermines compliance efforts and may result in regulatory penalties. The lack of a patch means organizations must rely on compensating controls, which may increase operational complexity. The vulnerability could also impact incident detection and response capabilities, as malicious traffic may evade logging and alerting mechanisms. Overall, this threat can degrade confidentiality protections and weaken defense-in-depth strategies in European enterprises.

1. Immediately assess the deployment of mad-proxy within your environment and identify all instances running version 0.3 or below. 2. Restrict mad-proxy usage to highly trusted network segments where exposure risk is minimized. 3. Implement network-level controls such as firewall rules and segmentation to limit access to mad-proxy and reduce attack surface. 4. Deploy additional monitoring solutions (e.g., IDS/IPS, network traffic analysis) to detect anomalous traffic patterns that may indicate bypass attempts. 5. Consider temporarily replacing mad-proxy with alternative, well-maintained proxy solutions that provide robust interception and filtering capabilities. 6. Enforce strict TLS inspection policies and certificate pinning where feasible to reduce the risk of unmonitored HTTPS traffic. 7. Maintain rigorous logging and audit trails for all proxy traffic to facilitate incident investigation. 8. Stay informed on vendor updates and apply patches promptly once a fix becomes available. 9. Conduct regular security assessments and penetration tests focusing on proxy infrastructure to identify potential bypasses or weaknesses. 10. Educate security teams about this vulnerability and incorporate it into threat modeling and risk management processes.