CVE-2025-3929: An XSS issue was discovered in MDaemon Email Server version 25.0.1 and below

Routine

MEDIUM 6.1UPGRADE

CVE-2025-3929 is a medium-severity flaw (CVSS 6.1) affecting email server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 50%)
CISA exploited list	No
Weakness	CWE-79
Published	2025-04-29
Last modified	2026-06-17

Publisher (CNA): ESET · Vendor: mdaemon

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-04-29 12:15 UTCPublished CVE record published
2026-06-17 09:20 UTCUpdated Record last modified

mdaemon email server UPGRADE

Affected: >= 20.0.0 and < 20.0.9 · >= 21.0.0 and < 21.0.8 · >= 21.5.0 and < 21.5.6 · >= 22.0.0 and < 22.0.7 · >= 23.0.0 and < 23.0.4 · >= 23.5.0 and < 23.5.5 · >= 24.0.0 and < 24.0.4 · >= 24.5.0 and < 24.5.3

Fixed in: 20.0.9, 21.0.8, 21.5.6, 22.0.7, 23.0.4, 23.5.5, 24.0.4, 24.5.3, 25.0.2

Safe to downgrade to: a release before 20.0.0

1. Check installed version

apt-cache policy email-server || rpm -q email-server || email-server --version

2. UPGRADE to 20.0.9 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade email-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade email-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 20.0.0 (Debian / Ubuntu)

apt-cache madison email-server sudo apt install email-server=<VERSION_BEFORE_20.0.0> sudo apt-mark hold email-server

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list email-server sudo dnf downgrade email-server-<VERSION_BEFORE_20.0.0> sudo dnf versionlock add email-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-3929?

email server: upgrade to 20.0.9, 21.0.8, 21.5.6, 22.0.7, 23.0.4, 23.5.5, 24.0.4, 24.5.3, 25.0.2. Exact commands for each OS are on this page.

Is CVE-2025-3929 being exploited?

CVE-2025-3929 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-3929 affect?

CVE-2025-3929 affects email server. Severity is medium (CVSS 6.1). 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 i

How urgent is CVE-2025-3929?

Priority 34/100. No elevated risk signals yet.

References

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