CVE-2026-48559
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedLightweight Music Server (LMS) though 3.76.0 contains a stored cross-site scripting vulnerability that allows attackers to execute arbitrary JavaScript by embedding malicious HTML in media file metadata tags such as GENRE, ARTIST, or ALBUM. Attackers can introduce a crafted media file into the victim's library, causing the payload to be saved during library scanning and executed automatically in the web interface due to tag content being rendered using Wt::TextFormat::UnsafeXHTML without sanitization in src/lms/ui/Utils.cpp.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceLightweight Music Server (LMS) through 3.76.0 has a stored XSS vulnerability where malicious HTML/JavaScript embedded in media file metadata tags (GENRE, ARTIST, ALBUM) is saved during library scanning and executed when rendered in the web interface. The vulnerability exists because tag content is rendered using Wt::TextFormat::UnsafeXHTML without sanitization in src/lms/ui/Utils.cpp.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed LMS versionRun 'lms --version' or check the application's about/help page. On Linux, also check /usr/share/lms or /opt/lms for version info if available.Affected if Version is 3.76.0 or any version lower than 3.76.0 (the vulnerability affects through 3.76.0)
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Verify library has been scannedCheck if the LMS database contains scanned media. Look for database files (usually in /var/lib/lms or ~/.lms) or check the web interface library view to confirm media files are present.Affected if The library contains scanned media files - this means metadata from those files has been processed and stored
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Inspect media file metadata for potential payloadsUse a tool like 'mediainfo', 'exiftool', or 'id3v2' to examine GENRE, ARTIST, and ALBUM tags on your media files. Look for HTML script tags, javascript: URLs, or event handlers (onclick, onerror, etc.).Affected if Any media file contains metadata with unescaped HTML characters or known XSS payloads in GENRE, ARTIST, or ALBUM fields
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Check web interface displays metadataLog into the LMS web interface and navigate to any view that displays artist, album, or genre information. Examine the page source (View > Developer > View Source) to see if metadata is rendered as raw HTML.Affected if The web interface renders metadata fields directly as HTML without encoding (you see actual HTML tags in the rendered page rather than escaped entities)
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Review source code for vulnerable functionIf you have access to the source, examine src/lms/ui/Utils.cpp and search for uses of Wt::TextFormat::UnsafeXHTML when rendering metadata.Affected if The code uses UnsafeXHTML to render any metadata field without prior sanitization
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Confirm database stores raw metadataIf you can access the LMS database directly (SQLite typically), query the media tables to see if metadata is stored exactly as read from files or if any sanitization occurs at storage time.Affected if Metadata in the database contains unescaped HTML special characters (< > " ') matching the original file tags
You are affected if you run LMS version 3.76.0 or lower, have scanned media files into your library, and the web interface displays GENRE, ARTIST, or ALBUM metadata rendered as raw HTML.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedReplace UnsafeXHTML rendering with sanitized HTML output or use Wt::TextFormat::XHTML with proper input validation/sanitization of media metadata before rendering.
Latest stable release beyond version 3.76.0 (check GitHub releases for the fixed version)
- 1. Identify the currently installed Lightweight Music Server (LMS) version by checking the application or package manager
- 2. Obtain the latest stable release of Lightweight Music Server from the official GitHub repository (github.com/epoupon/lms)
- 3. Before upgrading, backup the current LMS configuration and database to prevent data loss
- 4. Upgrade to the latest available version beyond 3.76.0 which contains the security fix for the stored XSS vulnerability
- 5. After upgrade, verify that media library scanning still functions correctly
- 6. Ensure the web interface renders metadata tags safely without the UnsafeXHTML vulnerability
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
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Free · runs locallyCheck whether your project pulls in CVE-2026-48559 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-48559 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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