CVE-2026-31864: JumpServer has a Server-Side Template Injection Leading to RCE via YAML Rendering

Vulnerability summary

CVE-2026-31864 is a medium (CVSS 6.8) vulnerability in fit2cloud jumpserver. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 30.8% of scored vulnerabilities.

Timeline

1. 13-03-2026
   PublishedVulnerability first disclosed.
2. 13-03-2026
   Last modifiedVulnerability information updated.

Description

JumpServer is an open source bastion host and an operation and maintenance security audit system. a Server-Side Template Injection (SSTI) vulnerability exists in JumpServer's Applet and VirtualApp upload functionality. This vulnerability can only be exploited by users with administrative privileges (Application Applet Management or Virtual Application Management permissions). Attackers can exploit this vulnerability to execute arbitrary code within the JumpServer Core container. The vulnerability arises from unsafe use of Jinja2 template rendering when processing user-uploaded YAML configuration files. When a user uploads an Applet or VirtualApp ZIP package, the manifest.yml file is rendered through Jinja2 without sandbox restrictions, allowing template injection attacks.

• CWE-1336Improper Neutralization of Special Elements Used in a Template EngineThe product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.