CVE-2025-53945 is a high-severity vulnerability identified in the chainguard-dev apko tool, which is used to build and publish OCI container images from apk packages. The vulnerability arises from incorrect default permissions set on critical files within apko versions starting from 0.27.0 up to but not including 0.29.5. Specifically, these files were inadvertently assigned permissions of 0666, meaning they were readable and writable by all users. This misconfiguration can be exploited to escalate privileges to root, as unauthorized users could modify critical files that influence container image builds or runtime behavior. The vulnerability is classified under CWE-276 (Incorrect Default Permissions), highlighting a failure to restrict access rights appropriately. The issue was addressed and fixed in version 0.29.5 of apko. The CVSS v3.1 base score is 7.0, indicating a high severity, with the vector AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L. This means the attack requires local access with high attack complexity and low privileges but no user interaction, and it can lead to a complete confidentiality breach, partial integrity loss, and partial availability impact with scope change. No known exploits are currently reported in the wild. The vulnerability affects users who build OCI container images using vulnerable apko versions, potentially compromising container security and the host environment if exploited.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on apko for container image creation and deployment in production or development environments. Exploitation could allow an attacker with local access to escalate privileges to root, potentially compromising containerized applications and the underlying host systems. This could lead to unauthorized data access, modification, or disruption of services. Given the widespread adoption of containerization in European enterprises, particularly in sectors such as finance, healthcare, and critical infrastructure, the vulnerability poses a risk to confidentiality, integrity, and availability of sensitive data and services. Additionally, compromised container images could propagate vulnerabilities downstream, affecting supply chain security. Organizations using CI/CD pipelines that incorporate apko are at risk of introducing compromised images into their environments, increasing the attack surface. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once the vulnerability details are public.

European organizations should immediately audit their use of apko to identify any deployments running affected versions (>=0.27.0 and <0.29.5). The primary mitigation is to upgrade apko to version 0.29.5 or later, where the incorrect permissions issue is resolved. Additionally, organizations should review file permission policies within their container build environments to ensure critical files are not globally writable. Implement strict access controls and monitoring on build servers to detect unauthorized modifications. Employ container image signing and verification to detect tampering. Integrate security scanning tools in CI/CD pipelines to identify vulnerable apko versions and misconfigurations early. Limit local user access to build environments to trusted personnel only, and consider using container runtime security tools to monitor for privilege escalation attempts. Regularly review and harden host OS security settings to reduce the impact of potential container breakout attempts. Finally, maintain an incident response plan tailored for container security incidents.