CVE-2026-84694 in Coolify
Summary
by MITRE • 09/02/2026
Coolify before 4.2.0 fails to properly escape environment variable key names in Docker commands executed over SSH on managed servers. Authenticated attackers can inject shell metacharacters into environment variable keys to execute arbitrary commands on the server host outside containers.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 09/02/2026
The vulnerability identified in Coolify versions prior to 4.2.0 represents a critical command injection flaw rooted in insufficient input validation and sanitization of user-supplied data within Docker management operations. Specifically, the application fails to properly escape environment variable key names when constructing shell commands that are executed over Secure Shell connections on managed servers. This architectural weakness allows authenticated users who possess valid credentials for the Coolify interface to manipulate the underlying command structure by injecting malicious shell metacharacters directly into the keys of environment variables. The core technical flaw lies in the application's handling of string interpolation, where user-controlled input is concatenated directly into system-level commands without adequate filtering or quoting mechanisms that would neutralize special characters such as semicolons, pipes, ampersands, and backticks.
From an operational perspective, this vulnerability enables arbitrary command execution on the host server outside of any containerized isolation boundaries. Because Coolify manages Docker environments via SSH, it inherently requires elevated privileges to interact with the Docker daemon and manage infrastructure resources. When an attacker successfully injects commands through environment variable keys, these injected payloads are executed by the root or privileged user account responsible for managing the containers on the host machine. This effectively bypasses container security boundaries, granting the attacker full control over the underlying operating system of the managed server. The impact is severe as it allows for complete compromise of the infrastructure, including potential lateral movement to other systems within the network, data exfiltration, and deployment of persistent backdoors or cryptomining software on the host OS.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-78, which describes Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The attack vector is classified under MITRE ATT&CK technique T1059, specifically subtechnique T1059.004 for Command and Scripting Interpreter abuse. Furthermore, because the exploitation requires prior authentication, it falls within the scope of CWE-287 regarding Improper Authentication or Authorization issues that lead to privilege escalation via command injection. The severity is exacerbated by the fact that Docker management tools often run with high privileges, making any successful exploit equivalent to gaining root access on the target host.
Mitigation strategies must prioritize immediate patching and strict input validation. Organizations running Coolify should upgrade to version 4.2.0 or later where this issue has been addressed through improved sanitization of environment variable keys before they are passed to shell commands. In environments where upgrading is not immediately feasible, administrators can implement compensating controls such as restricting SSH access to only trusted IP addresses and enforcing multi-factor authentication for Coolify accounts to reduce the attack surface. Additionally, deploying network-level intrusion detection systems that monitor for anomalous command patterns in Docker-related traffic may help detect exploitation attempts. It is also advisable to review audit logs on managed servers for any unauthorized shell commands originating from the Coolify service account to assess potential compromise history and ensure no persistent threats remain active on the host system.