JumpServer up to 3.10.21/4.10.15 YAML Configuration special elements used in a template engine

Summaryinfo

A vulnerability has been found in JumpServer up to 3.10.21/4.10.15 and classified as problematic. This issue affects some unknown processing of the component YAML Configuration Handler. This manipulation causes improper neutralization of special elements used in a template engine. This vulnerability is registered as CVE-2026-31864. Remote exploitation of the attack is possible. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in JumpServer up to 3.10.21/4.10.15. It has been declared as problematic. Affected by this vulnerability is an unknown part of the component YAML Configuration Handler. The manipulation with an unknown input leads to a improper neutralization of special elements used in a template engine vulnerability. The CWE definition for the vulnerability is CWE-1336. The 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. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-31864 since 03/09/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation requires an enhanced level of successful authentication. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1221 for this issue.

Upgrading to version 3.10.22 or 4.10.16 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• JumpServer

Version

• 3.10.0
• 3.10.1
• 3.10.2
• 3.10.3
• 3.10.4
• 3.10.5
• 3.10.6
• 3.10.7
• 3.10.8
• 3.10.9
• 3.10.10
• 3.10.11
• 3.10.12
• 3.10.13
• 3.10.14
• 3.10.15
• 3.10.16
• 3.10.17
• 3.10.18
• 3.10.19
• 3.10.20
• 3.10.21
• 4.10.0
• 4.10.1
• 4.10.2
• 4.10.3
• 4.10.4
• 4.10.5
• 4.10.6
• 4.10.7
• 4.10.8
• 4.10.9
• 4.10.10
• 4.10.11
• 4.10.12
• 4.10.13
• 4.10.14
• 4.10.15

Website

• Product: https://github.com/jumpserver/jumpserver/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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