# CVE-2025-66645: NiceGUI Path Traversal Vulnerability in app.add_media_files() Allows Arbitrary File Reading

> A remote attacker can read arbitrary files on the server filesystem via directory traversal in NiceGUI's add_media_files function.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Dec 2025
- **Updated:** 10 Dec 2025
- **Also known as:** GHSA-hxp3-63hc-5366, PYSEC-2026-1700

## What is CVE-2025-66645?

CVE-2025-66645 is a high-severity path traversal vulnerability in zauberzeug nicegui, published on 9 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

NiceGUI is a Python-based UI framework. Versions 3.3.1 and below are vulnerable to  directory traversal through the App.add_media_files() function, which allows a remote attacker to read arbitrary files on the server filesystem. This issue is fixed in version 3.4.0.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2025-66645?

3 open source packages ship an affected version, including nicegui. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nicegui` | PyPI | All versions | 3.4.0 |
| `nicegui` | PyPI | All versions | 3.4.0 |
| `nicegui` | PyPI | All versions | 3.4.0 |

Products: Zauberzeug Nicegui.

## How do I fix CVE-2025-66645?

Upgrade nicegui to 3.4.0 or later.

## Is CVE-2025-66645 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-66645 exists.

Public exploit code:

- NiceGUI Path Traversal CTF Challenge (github_poc): https://github.com/prokeon5991-wq/cve-2025-66645

## Other vulnerabilities in zauberzeug nicegui

- [CVE-2026-25732](https://insights.sbomify.com/CVE-2026-25732/): NiceGUI's Path Traversal via Unsanitized FileUpload.name Enables Arbitrary File Write (high 7.5)
- [CVE-2026-21873](https://insights.sbomify.com/CVE-2026-21873/): Zero-click XSS in all NiceGUI apps which uses `ui.sub_pages` (high 7.2)
- [CVE-2026-33332](https://insights.sbomify.com/CVE-2026-33332/): NiceGUI's unvalidated chunk size parameter in media routes can cause memory exhaustion (medium 6.9)
- [CVE-2026-27156](https://insights.sbomify.com/CVE-2026-27156/): NiceGUI has XSS via Code Injection (medium 6.1)
- [CVE-2026-25516](https://insights.sbomify.com/CVE-2026-25516/): NiceGUI's XSS vulnerability in ui.markdown() allows arbitrary JavaScript execution through unsanitized HTML content (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-66645 and fix it if it is affected.

What it is: CVE-2025-66645 is a high-severity path traversal vulnerability in zauberzeug nicegui, published on 9 Dec 2025. 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-2025-66645 exists.

Affected packages and fixed versions:
- nicegui (PyPI): affected all versions; fixed in 3.4.0
- nicegui (PyPI): affected all versions; fixed in 3.4.0
- nicegui (PyPI): affected all versions; fixed in 3.4.0

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-2025-66645/ (Markdown: https://insights.sbomify.com/CVE-2025-66645/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-66645
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-66645
- OSV: https://osv.dev/vulnerability/CVE-2025-66645

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-66645/
Summaries are generated and may contain mistakes; the official description above is the record.