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

> Remote attackers can bypass authentication via Host header spoofing to inject downloads, write files, and execute JavaScript in pyLoad.

- **Severity:** High 8.8 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Mar 2026
- **Updated:** 25 Mar 2026
- **Also known as:** GHSA-g5j2-gxqh-x7pw

## What is CVE-2026-33511?

CVE-2026-33511 is a high-severity authentication bypass vulnerability in pyload, published on 24 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-33511?

It affects 2 products.


Products: Pyload-Ng Project Pyload-Ng, Pyload Pyload.

## How do I fix CVE-2026-33511?

No fix has been published for CVE-2026-33511 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-33511 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33511 exists.

## Other vulnerabilities in pyload

- [CVE-2025-54802](https://insights.sbomify.com/CVE-2025-54802/): pyLoad CNL Blueprint is vulnerable to Path Traversal through `dlc_path` leading to Remote Code Execution (RCE) (critical 9.8)
- [CVE-2024-22416](https://insights.sbomify.com/CVE-2024-22416/): Cross-Site Request Forgery on any API call in pyLoad may lead to admin privilege escalation (critical 9.7)
- [CVE-2023-0488](https://insights.sbomify.com/CVE-2023-0488/): Cross-site Scripting (XSS) - Stored in pyload/pyload (critical 9.6)
- [CVE-2026-35459](https://insights.sbomify.com/CVE-2026-35459/): pyLoad has SSRF fix bypass via HTTP redirect (critical 9.3)
- [CVE-2026-35463](https://insights.sbomify.com/CVE-2026-35463/): pyLoad has Improper Neutralization of Special Elements used in an OS Command (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33511 and fix it if it is affected.

What it is: CVE-2026-33511 is a high-severity authentication bypass vulnerability in pyload, published on 24 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33511 exists.

Affected product: pyload. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-33511/ (Markdown: https://insights.sbomify.com/CVE-2026-33511/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33511
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33511
- OSV: https://osv.dev/vulnerability/CVE-2026-33511

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33511/
Summaries are generated and may contain mistakes; the official description above is the record.