Compliance Impact

The vulnerability allows attackers to execute arbitrary JavaScript via stored cross-site scripting (XSS) in media file metadata tags. This can lead to unauthorized access or manipulation of user data through the web interface.

Such unauthorized data access or manipulation could potentially violate data protection regulations like GDPR or HIPAA, which require safeguarding personal and sensitive information against unauthorized access or breaches.

However, the provided information does not explicitly discuss the impact of this vulnerability on compliance with these standards.

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Executive Summary

CVE-2026-48559 is a stored cross-site scripting (XSS) vulnerability in Lightweight Music Server (LMS) version 3.76.0 and earlier.

The vulnerability occurs because the application improperly handles media file metadata tags such as GENRE, ARTIST, or ALBUM. If an attacker embeds malicious HTML or JavaScript code into these tags, the payload is saved during the library scanning process.

Later, when the media file information is displayed in the LMS web interface, the malicious code executes automatically because the tag content is rendered using an unsafe method (Wt::TextFormat::UnsafeXHTML) without proper sanitization.

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Impact Analysis

This vulnerability allows attackers to execute arbitrary JavaScript code in the context of the LMS web interface.

• Attackers can upload specially crafted media files containing malicious metadata to trigger the XSS.
• Successful exploitation can lead to session hijacking, theft of sensitive information, or unauthorized actions performed on behalf of the victim user.
• Because the attack is stored, the malicious code persists in the system and executes whenever the affected media metadata is viewed.

Overall, this poses a moderate security risk to users of the LMS web interface.

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Detection Guidance

This vulnerability can be detected by identifying media files in the Lightweight Music Server library that contain malicious HTML or JavaScript embedded in metadata tags such as GENRE, ARTIST, or ALBUM.

One approach is to scan media files for suspicious or unusual HTML or JavaScript code within these metadata tags.

For example, you can extract metadata from media files using command-line tools like 'ffprobe' or 'exiftool' and then search for suspicious content.

• Use ffprobe to extract metadata: ffprobe -v quiet -show_entries format_tags=GENRE,ARTIST,ALBUM -of default=noprint_wrappers=1:nokey=1 <mediafile>
• Use exiftool to extract metadata: exiftool -GENRE -ARTIST -ALBUM <mediafile>

After extracting metadata, search for suspicious tags containing HTML or JavaScript code using grep or similar tools.

• grep -iE '<script|<.*onerror|<.*onclick' metadata_output.txt

Additionally, monitoring the web interface for unexpected script execution or unusual behavior when viewing media file details can help detect exploitation.

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Mitigation Strategies

Immediate mitigation steps include preventing the introduction of crafted media files containing malicious metadata into the Lightweight Music Server library.

You should avoid uploading or adding untrusted media files to the server until a patch is applied.

Restrict user permissions to limit who can add media files to the library, reducing the risk of malicious file uploads.

Monitor and review media file metadata for suspicious content before adding files to the library.

Apply the official fix by upgrading Lightweight Music Server to version 3.77.0 or later, where this vulnerability is addressed.

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