CVE-2019-8341

CRITICAL

Jinja2 2.10 - 'from_string' Server Side Template Injection

Title source: exploit-db.com
Search associated code STIX 2.1 vulnerability STIX 2.1 with PoCs

Record summary

CVE-2019-8341 has a selected CVSS score of 9.8 (critical); EIP currently links 1 catalogued exploit, 1 repository PoC, and 1 lab environment.

Description

An issue was discovered in Jinja2 2.10. The from_string function is prone to Server Side Template Injection (SSTI) where it takes the "source" parameter as a template object, renders it, and then returns it. The attacker can exploit it with {{INJECTION COMMANDS}} in a URI. NOTE: The maintainer and multiple third parties believe that this vulnerability isn't valid because users shouldn't use untrusted templates without sandboxing

Description source: CVE List

Exploitation context

Available material

Catalogued exploits
1
Repository PoCs
1
Lab environments
1

Proofs of concept

2

Catalogued exploits

ExploitDBJinja2 2.10 - 'from_string' Server Side Template InjectionExploitDB exploitby JameelNabboNot analyzed1 file
ExploitDB
PoC details

Repository PoCs

GitHubadindrabkin/llama_factsRepository PoCby adindrabkin0Not analyzed22 files

2.5 MiB

GitHub
PoC details

Docker lab environments

1
GitHub

Repository root

adindrabkin/llama_factsCreated Vuln labCVE-2019-8341Dockerfile

1 Dockerfile

View exploit
Analysisdeepseek-v4-pro:cloud ·

Environment assessment

A Dockerized Flask web application that serves a blog about llamas and includes a search feature. The README states it is intentionally vulnerable to Server-Side Template Injection (SSTI) and was created for a CTF competition.

README.md:2-3Dockerfile:1-15

Lab assessment

Vulnerability lab

The README explicitly states the project is vulnerable to SSTI (CVE-2019-8341) and was created for a CTF competition. The source code contains a Flask endpoint that uses render_template_string on user input, which is a classic SSTI vulnerability.

README.md:2-3src/server.py:20-26
Lab shapeDockerfile
ServicesUnknown
Compose manifests0
Dockerfiles1
Evidence & reasoningComponents · CVE assessment · exercise context · review boundaries
Components

Services and files described by the evidence

Flask web application

vulnerable targetweb server

A Python Flask app that serves static content and a search endpoint. The /search route takes user input from a POST form, passes it to render_template_string without sanitization, enabling SSTI. It also serves a flag file at /app/flag.txt, which is likely the CTF objective.

src/server.py:1-71Dockerfile:8

Docker environment

containerizationlab boundary

A Dockerfile based on python:3.9 that copies the application source, requirements, and flag file into /app, installs dependencies from local wheels, exposes port 5656, and runs the Flask server.

Dockerfile:1-15

Build and run script

convenience script

A shell script that builds the Docker image and runs a container with port 5656 mapped to the host.

build_run.sh:1
CVE assessment

How the supplied evidence relates each vulnerability

CVE-2019-8341

Supported by supplied evidence

The README states the project is vulnerable to CVE-2019-8341, which is a disputed Jinja2 SSTI vulnerability. The code uses render_template_string on user-controlled input (query) without sanitization, matching the described vulnerability.

README.md:2-3src/server.py:20-26
Exercise context

Requirements and sequence described by the evidence

Prerequisites

  • Docker engine installed and running.README.md:8
  • Build the Docker image and run the container with port mapping.README.md:10

Evidence-described exercise path

  1. Navigate to http://localhost:5656.README.md:12
  2. Use the search form to submit a payload that exploits the SSTI vulnerability in the /search endpoint.src/server.py:20-26src/content/home.html:40-50
  3. Retrieve the flag from /app/flag.txt using SSTI to read the file.Dockerfile:8flag.txt:1
Safety-review evidence

Behaviors behind the stored safety assessment

No harmful behavior observed

The visible behavior is limited to a Flask application serving a CTF challenge. The Dockerfile copies only local files, installs dependencies from local wheels, and exposes a single port. No evidence of host escape, external connections, persistence, credential theft, or destructive actions. The port mapping and flag file are consistent with a contained lab exercise.

Dockerfile:1-15src/server.py:1-71build_run.sh:1
Review boundaries

What the analysis did not establish

  • 9 binary files are uninspected, including .tar.gz archives and image files; their contents are not analyzed.
  • 4 oversized source files (click, Flask, Jinja2, Werkzeug) are omitted and uninspected.
  • The writeup.md file is listed in the file inventory but its content is not included in evidence_files.
  • The Dockerfile uses --no-index and local wheels, but the contents of those wheels are not fully inspected.
Model interpretation

This review is limited to the supplied lab evidence packet. It does not assert that the environment runs, reproduces a vulnerability, or is safe to execute. Contract: eip-docker-lab-analysis-v1.

Packet coverage: some source evidence omitted · 9 binary files not inspected

References

7