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

Severity: medium (CVSS 6.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-13 · updated 2026-06-17
Weakness: CWE-1336

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.

Affected products

jumpserver: before 3.10.22; from 4.0.0 before 4.10.16 — fixed in 3.10.22, 4.10.16

How to fix

Upgrade to a fixed version: jumpserver 3.10.22, 4.10.16. Check the vendor advisory for mitigations.

References

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