CVE-2025-70819 in D6 Ultra
Summary
by MITRE • 09/13/2026
Zettlab D6 Ultra before 1.7.0 allows mounting /etc/passwd and /etc/shadow in a container via ".." manipulations such as volumes: - ../../../../../../../etc:/h_etc:rw in a compose file.
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Analysis
by VulDB Data Team • 09/13/2026
The vulnerability identified in Zettlab D6 Ultra versions prior to 1.7.0 represents a critical Container Escape and Host Filesystem Access flaw, specifically categorized under CWE-284 Improper Access Control and CWE-59 Improper Link Resolution Before Active Use or During Upgrade. This security defect arises from insufficient validation of volume mount paths within the container orchestration configuration files, allowing an attacker to manipulate relative path traversals using dot-dot-slash sequences such as ../../../../../../../etc. By exploiting this mechanism, a malicious actor can bypass intended isolation boundaries and gain direct read-write access to sensitive host system files including /etc/passwd and /etc/shadow.
In the context of containerized environments like Docker Compose, volume mounts are designed to bind directories from the host machine into the container's filesystem for data persistence or sharing. However, when path validation is lax, attackers can utilize relative path traversal techniques to escape the designated mount point directory. The specific example provided demonstrates how a simple configuration entry volumes: - ../../../../../../../etc:/h_etc:rw allows mapping the entire /etc directory from the host into the container at the location h_etc with read-write permissions. This effectively neutralizes the security boundary that containers are supposed to enforce, granting processes running inside the container unrestricted access to critical system authentication files on the underlying operating system.
The operational impact of this vulnerability is severe and multifaceted. Access to /etc/passwd allows an attacker to enumerate valid user accounts on the host system, which facilitates further reconnaissance and targeted attacks such as password spraying or credential stuffing if weak passwords are in use. More critically, access to /etc/shadow enables offline cracking of hashed passwords due to its read-write nature. If successful, this leads to full account compromise, allowing privilege escalation from a low-privileged container user to root-level administrative control over the host machine. This scenario aligns with MITRE ATT&CK techniques T1078 Valid Accounts and potentially T1546 Event Triggered Execution if combined with other exploits for persistence or lateral movement within the network infrastructure.
Mitigation strategies must focus on strict input validation and least-privilege principles in container orchestration configurations. Administrators should ensure that volume mount paths are absolute rather than relative to prevent path traversal attacks, although even absolute paths require careful auditing to avoid unintended host exposure. Upgrading Zettlab D6 Ultra to version 1.7.0 or later is the primary remediation step as it addresses this specific flaw in path handling logic. Additionally, organizations should implement runtime security controls such as AppArmor or SELinux profiles that restrict container access to sensitive host directories regardless of volume mount configurations. Regular auditing of Docker Compose files and CI/CD pipelines for insecure volume mappings can further reduce the attack surface by preventing these misconfigurations from reaching production environments.