CVE-2024-21644 is a high-severity (CVSS 7.5) vulnerability in pyload-ng. 1 public exploit reference exists, so weaponization risk is real. A fix is available for pyload-ng — see the affected versions and patch details below.
pyLoad unauthenticated flask configuration leakage
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-21644.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2024-21644 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
pyload-ngReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Any unauthenticated user can browse to a specific URL to expose the Flask config, including the SECRET_KEY variable.
Details
Any unauthenticated user can browse to a specific URL to expose the Flask config, including the SECRET_KEY variable.
PoC
Run pyload in the default configuration by running the following command
pyload
Now browse to http://localhost:8000/render/info.html. Notice how the Flask configuration gets displayed.
I was quite amused by this finding. I think it's a very interesting coming together of things that is so unlikely to happen. Below I will detail my process a bit more.
I was looking through the code to see how the authorization mechanism is implemented when I spotted this route, which can be accessed by any unauthenticated actor
@bp.route("/render/<path:filename>", endpoint="render")
def render(filename):
mimetype = mimetypes.guess_type(filename)[0] or "text/html"
data = render_template(filename)
return flask.Response(data, mimetype=mimetype)
This route allows me to load in any of the predefined templates. However, these templates will be lacking any form of context, and as such it doesn't seem too useful. That is until I loaded the info.html template and scrolled down, revealing the Flask config. This was purely accidental, and I did not understand why it happened, until I looked at the template
<tr>
<td>{{ _("Config folder:") }}</td>
<td>{{ config }}</td>
</tr>
In Flask, every template always gets the Flask config passed to it as the config variable. In the normal execution of this template, this value gets overwritten in the function below, but since we're calling it and bypassing this function altogether, it doesn't get overwritten. Would this variable not be named config and named configuration or Config instead, then this exploit wouldn't work. The likelihood of this occurring is so small, but it seems to have happened here.
context = {
"python": sys.version,
"os": " ".join((os.name, sys.platform) + extra),
"version": api.get_server_version(),
"folder": PKGDIR,
"config": api.get_userdir(),
"download": conf["general"]["storage_folder"]["value"],
"freespace": format.size(api.free_space()),
"webif": conf["webui"]["port"]["value"],
"language": conf["general"]["language"]["value"],
}
return render_template("info.html", **context)
Impact
Depending on the how the Flask config data is used, it could have detrimental consequences for the security. It's crucial to keep the SECRET_KEY secret and never expose it in your code or configuration files.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pyload-ng | all versions | 0.5.0b3.dev77pip install --upgrade 'pyload-ng==0.5.0b3.dev77' |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyload-ng, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pyload-ng to 0.5.0b3.dev77 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-21644 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-21644 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-21644. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
How to detect CVE-2024-21644
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2024-21644 -u https://target- Template
- pyLoad Flask Config - Access Control
- Severity
- high
- Impact
- Unauthenticated attackers can access the Flask SECRET_KEY and other sensitive configuration variables, potentially enabling session hijacking or other attacks.
- Remediation
- Update pyLoad to version 0.5.0b3.dev77 or later.
Template by ProjectDiscovery nuclei-templates (West-wise), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2024-21644 in your dependencies?
O3 Security finds CVE-2024-21644 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.