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Email ServerApplication · Mdaemon

CVE-2025-3929

MEDIUM · 6.1 CVSS v3.1 Published 2025-04-29
Fix available
A fix is available. Upgrade to 20.0.9 / 21.0.8 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

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 · unedited
An XSS issue was discovered in MDaemon Email Server version 25.0.1 and below. An attacker can send a specially crafted HTML e-mail message with JavaScript in an img tag. This could allow a remote attacker to load arbitrary JavaScript code in the context of a webmail user's browser window, and access user data.

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 confidence

A stored Cross-Site Scripting (XSS) vulnerability in MDaemon Email Server's webmail interface allows remote attackers to inject malicious JavaScript via specially crafted HTML emails containing script in img tags. When users view these emails through webmail, the embedded JavaScript executes in their browser context, enabling session hijacking and unauthorized access to user data.

MitigationApply the vendor-supplied patch for MDaemon Email Server 25.0.1 and below. As an interim measure, disable HTML email rendering in webmail or implement Content Security Policy headers to block inline script execution.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Email ServerApplication
Affected:>= 20.0.0, < 20.0.9>= 21.0.0, < 21.0.8>= 21.5.0, < 21.5.6>= 22.0.0, < 22.0.7>= 23.0.0, < 23.0.4>= 23.5.0, < 23.5.5>= 24.0.0, < 24.0.4>= 24.5.0, < 24.5.3>= 25.0.0, < 25.0.2

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
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check MDaemon Email Server version
    Open the MDaemon console or check the About section in MDaemon to view the installed version number
    Affected if The installed version falls within any of these ranges: 20.0.0 to 20.0.8, 21.0.0 to 21.0.7, 21.5.0 to 21.5.5, 22.0.0 to 22.0.6, 23.0.0 to 23.0.3, 23.5.0 to 23.5.4, 24.0.0 to 24.0.3, 24.5.0 to 24.5.2, or 25.0.0 to 25.0.1
  2. Verify webmail interface is enabled
    Check MDaemon configuration to confirm the webmail service is active and accessible to users
    Affected if Webmail is enabled and users can log in to view emails through the web interface
  3. Confirm HTML email rendering is enabled
    Check MDaemon webmail settings for the option that allows HTML emails to be rendered rather than displayed as plain text
    Affected if HTML rendering is enabled and users can view HTML-formatted emails in webmail

You are affected if your MDaemon version is within the affected ranges AND webmail with HTML email rendering is enabled, allowing users to view malicious HTML emails containing script tags in img elements.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 20.0.9 / 21.0.8 / 21.5.6 or later
Fixed in 20.0.921.0.821.5.6
Interim mitigation

Apply the vendor-supplied patch for MDaemon Email Server 25.0.1 and below. As an interim measure, disable HTML email rendering in webmail or implement Content Security Policy headers to block inline script execution.

Recommended fix Moderate confidence

20.0.9 (for v20.x), 21.0.8 (for v21.x), 21.5.6 (for v21.5.x), or 22.0.7 (for v22.x)

  1. 1. Identify the currently installed MDaemon Email Server version by checking the application or using the version information in the admin interface.
  2. 2. Based on your current major version, plan the upgrade to the corresponding fixed release:
  3. - If running 20.x: upgrade to 20.0.9
  4. - If running 21.x (non-21.5): upgrade to 21.0.8
  5. - If running 21.5.x: upgrade to 21.5.6
  6. - If running 22.x: upgrade to 22.0.7
  7. 3. Before upgrading, backup the MDaemon configuration, data directories, and any custom settings.
  8. 4. Download the appropriate fixed version from the official MDaemon download area at mdaemon.com.
Caveat Standard MDaemon upgrades typically preserve settings; however, always backup before upgrading as with any software update

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Email Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-3929 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data