Description

JumpServer is an open source bastion host and an operation and maintenance security audit system. Prior to 4.10.17, an authenticated administrator with Applet Host management and deployment permissions can inject Jinja2 expressions into the IP/Host field or Core Service Address field, causing Ansible to evaluate ansible_host inventory data or playbook variables during Applet Host deployment and execute arbitrary commands on the JumpServer control node. This issue is fixed in version 4.10.17.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.7",
  "pubDate": "2026-08-17T21:16:45.083Z",
  "pubdate": "2026-08-17T21:16:45.083Z",
  "executiveSummary": "JumpServer prior to version 4.10.17 suffers from an administrative-level template injection vulnerability that enables remote code execution on the control node. The flaw involves the insecure handling of user-supplied input within the Applet Host management and deployment functionalities, specifically targeting fields processed by the Ansible automation engine. An authenticated adversary possessing specific administrative permissions can supply malicious Jinja2 template expressions disguised as standard network or service parameters. When JumpServer initiates Applet Host deployment routines, the underlying Ansible engine inadvertently parses and evaluates these injected template expressions against inventory data and playbook variables. Successful exploitation grants the attacker the ability to execute arbitrary operating system commands with the privilege level of the JumpServer control node process. This compromises the integrity, confidentiality, and availability of the entire bastion host architecture and managed infrastructure. Mitigation requires updating the JumpServer deployment to version 4.10.17 or later, where input sanitization and expression evaluation controls are properly enforced to neutralize template injection vectors.",
  "technicalDetails": "The vulnerability resides within the Applet Host management and deployment components of JumpServer prior to version 4.10.17. The root cause is the improper sanitization and subsequent unsafe evaluation of administrative input fields—specifically the IP/Host field and the Core Service Address field—by the underlying Ansible automation framework. JumpServer utilizes Ansible to orchestrate deployments, passing user-provided parameters as inventory data or playbook variables.\nAuthentication and privilege requirements dictate that the attacker must possess an authenticated administrator session with specific permissions for Applet Host management and deployment. Within this authenticated context, the attacker injects specially crafted Jinja2 template syntax into the vulnerable IP/Host or Core Service Address input fields during host configuration routines.\nThe attack flow proceeds as follows: 1. The authenticated administrator navigates to the Applet Host configuration interface. 2. The malicious payload, formatted as a Jinja2 expression designed to invoke system execution modules or evaluate dangerous template constructs, is entered into the targeted fields and submitted. 3. JumpServer stores the configuration and subsequently initiates an Ansible-based deployment routine for the Applet Host. 4. During execution, Ansible parses the inventory data and playbook variables containing the unvalidated input. 5. The Jinja2 engine evaluates the injected expressions within the context of the JumpServer control node. 6. Arbitrary system commands embedded within the template payload are executed directly on the control node operating system.\nThe post-exploitation impact allows the attacker to achieve full remote code execution on the JumpServer control node, potentially facilitating privilege escalation, lateral movement across managed target systems, data exfiltration, and complete compromise of the bastion host security perimeter."
}