What is the CVSS score of CVE-2025-34491?

CVE-2025-34491 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 1.2%.

Which versions of Mailessentials are affected by CVE-2025-34491?

Organizations using GFI MailEssentials prior to version 21.8 face significant risk from CVE-2025-34491, a insecure deserialization vulnerability rated CVSS 8.8.

Is there a public PoC exploit available for CVE-2025-34491?

Yes, a public proof-of-concept exploit is available for CVE-2025-34491. Prioritise patching immediately. EPSS: 1.2%.

How to fix or mitigate CVE-2025-34491?

Within 7 days: Identify all affected systems and apply vendor patches promptly. Restrict deserialization to trusted data sources and implement integrity checks.

Mailessentials CVE-2025-34491

HIGH

Deserialization of Untrusted Data (CWE-502)

2025-04-28 disclosure@vulncheck.com

RCE Deserialization Mailessentials

8.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

8.8 HIGH

AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:39 vuln.today

PoC Detected

Nov 04, 2025 - 23:15 vuln.today

Public exploit code

CVE Published

Apr 28, 2025 - 20:15 nvd

HIGH 8.8

DescriptionCVE.org

GFI MailEssentials prior to version 21.8 is vulnerable to a .NET deserialization issue. A remote and authenticated attacker can execute arbitrary code by sending crafted serialized .NET when joining to a Multi-Server setup.

AnalysisAI

GFI MailEssentials prior to version 21.8 is vulnerable to a .NET deserialization issue. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.

Technical ContextAI

This vulnerability is classified as Deserialization of Untrusted Data (CWE-502), which allows attackers to execute arbitrary code through malicious serialized objects. GFI MailEssentials prior to version 21.8 is vulnerable to a .NET deserialization issue. A remote and authenticated attacker can execute arbitrary code by sending crafted serialized .NET when joining to a Multi-Server setup. Affected products include: Gfi Mailessentials. Version information: version 21.8.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Avoid deserializing untrusted data. Use safe serialization formats (JSON). Implement integrity checks and type allowlists.