A recently identified vulnerability in Docker Desktop’s Registry Access Management (RAM) feature has exposed macOS users to potential security breaches by permitting unauthorized container image pulls. This flaw, designated as CVE-2025-4095, undermines essential container security protocols, allowing developers to bypass registry restrictions set by administrators.
Understanding the Vulnerability
Docker’s Registry Access Management is designed to restrict container image pulls to approved registries, such as Docker Hub, Amazon ECR, or private artifact repositories. By implementing DNS-level blocklists, RAM prevents developers from accessing untrusted sources, thereby enhancing supply chain security.
However, when organizations enforce sign-in policies on macOS through configuration profiles—a common method for enterprise deployments—RAM policies fail to activate. This issue arises from a misconfiguration in Docker Desktop’s policy enforcement engine. On macOS, Docker operates within a Hyperkit virtual machine, applying RAM policies at the daemon level after user authentication. Configuration profiles, which are XML or mobileconfig files used to automate settings, improperly prioritize sign-in enforcement over RAM initialization. This sequence creates a race condition where the Docker daemon starts before RAM policies load, leaving registries unrestricted until the next system reboot.
Affected Versions and Risk Assessment
The vulnerability affects Docker Desktop versions 4.36.0 through 4.40.x on macOS. While the Common Vulnerability Scoring System (CVSS) v4.0 assigns it a score of 4.3 (Medium), the operational risks are significant. Attackers could exploit this gap to inject malicious images into development pipelines, leading to severe security incidents.
Potential Impacts on Container Security
Organizations relying on RAM to comply with standards like NIST SP 800-190 or the SLSA Framework face immediate exposure due to this vulnerability:
– Unrestricted Image Pulls: Developers can access public registries like Docker Hub, even if blocked by policy, reintroducing risks from typosquatted or compromised packages.
– Credential Leakage: If attackers compromise a developer’s machine, they could push stolen credentials to unauthorized registries without triggering alerts.
– CI/CD Compromise: Malicious images could infiltrate build systems, leading to privilege escalation or data exfiltration.
Docker’s internal testing confirmed that RAM policies remain inactive for up to 24 hours after initial sign-in when configuration profiles are used, providing ample time for exploitation.
Mitigation and Recommendations
Docker has released fixes in Desktop version 4.41.0, which decouples RAM initialization from sign-in workflows. Administrators are advised to:
– Upgrade: Immediately update all macOS Docker Desktop instances to version 4.41.0 or later.
– Verify Enforcement: Use the command `docker info | grep -i registry` to confirm allowed registries and ensure RAM enforcement.
– Transition to Admin Console Enforcement: Instead of configuration profiles, enforce sign-in via Docker’s centralized console, which properly sequences policy loads.
For organizations unable to patch immediately, workarounds include:
– Manual Policy Enforcement: Manually configure RAM policies post-sign-in to ensure they are active.
– Monitoring and Alerts: Implement monitoring tools to detect unauthorized image pulls and set up alerts for suspicious activities.
Broader Implications and Historical Context
This vulnerability highlights the critical importance of securing container registries and the potential risks associated with misconfigurations. Similar issues have been observed in the past:
– Misconfigured Docker Registries: Research has shown that thousands of Docker registries are exposed to the internet without proper authentication, allowing unauthorized access to sensitive code repositories. Such exposures can lead to intellectual property theft, data breaches, and the injection of malicious code.
– Harbor Registry Vulnerability: A critical flaw in Harbor, an open-source container image registry, allowed attackers to elevate privileges to administrator levels, potentially leading to the compromise of entire registries.
These incidents underscore the necessity for organizations to implement robust security measures, including proper access controls, regular audits, and timely application of patches to protect their container environments.
Conclusion
The discovery of CVE-2025-4095 in Docker Desktop for macOS serves as a stark reminder of the complexities involved in container security. Organizations must remain vigilant, ensuring that security policies are correctly implemented and regularly updated to mitigate potential vulnerabilities. By promptly addressing this issue through the recommended updates and best practices, organizations can safeguard their development pipelines against unauthorized access and potential security breaches.
