mcp-contextforge-gateway has Server-Side Template Injection (SSTI) leading to Remote Code Execution in PromptService._render_template via unsandboxed Jinja2 Environment

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary mcpgateway.services.promptservice.PromptService renders user-supplied prompt templates using Jinja2's plain Environment() rather than SandboxedEnvironment. An authenticated user with permission to register or update prompt templates can store a malicious template that, on subsequent rendering, executes arbitrary Python code on the gateway host with the privileges of the gateway process. This is a Server-Side Template Injection (SSTI) vulnerability leading to Remote Code Execution. Details Affected component: mcpgateway/services/promptservice.py Affected version: 0.9.0 (verified). The fix in the unreleased main branch indicates all earlier published versions are likewise affected. Vulnerable code mcpgateway/services/promptservice.py, line 26: mcpgateway/services/promptservice.py, line 135 (inside PromptService.init): mcpgateway/services/promptservice.py, lines 1592–1616 (rendertemplate): rendertemplate is invoked from PromptService.getprompt (line 892): Where prompt.template…

Published by the source

25 Aug 2026, 17:42 UTC

Last modified by the source

25 Aug 2026, 17:42 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-vwf3-4xxj-qg6h

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# Patch Next advisory brief: GHSA-vwf3-4xxj-qg6h

Advisory: mcp-contextforge-gateway has Server-Side Template Injection (SSTI) leading to Remote Code Execution in `PromptService._render_template` via unsandboxed Jinja2 Environment
IDs: GHSA-vwf3-4xxj-qg6h
Record: https://patchnext.com/advisories/ghsa-vwf3-4xxj-qg6h (revision 1, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mcp-contextforge-gateway 1.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI mcp-contextforge-gateway: affected < 1.0.0; fixed in 1.0.0

## Suggested inspection (read-only)
- `python -m pip show mcp-contextforge-gateway`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mcp-contextforge-gateway.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-vwf3-4xxj-qg6h (GitHub-reviewed advisory GHSA-vwf3-4xxj-qg6h lists affected ranges: PyPI mcp-contextforge-gateway >=0 <1.0.0)

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