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VulnerabilityPublished Updated

CVE-2025-34491: GFI MailEssentials · Deserialization of Untrusted Data

Affects GFI MailEssentialsSource GCVE Database

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Not known to be exploited · CVSS 8.8 High : upgrade to 21.8 soon.

Data as of 13 Nov 2026, 20:18 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 3.18.8
Patch
Available – fixed in 21.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 28 Apr 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade GFI MailEssentials to 21.8.

Affected software

ProductAffectedFixed in
GFI MailEssentialsAffected
  • <21.8
Fixed in
  • 21.8

AI-suggested

Upgrade GFI MailEssentials to version 21.8 or later, where this vulnerability is fixed. No other mitigation or workaround is indicated in the available data.

Description

GFI MailEssentials versions prior to 21.8 contain a deserialization vulnerability in their .NET implementation. This flaw allows a remote authenticated attacker to execute arbitrary code by sending crafted serialized .NET data when joining a Multi-Server setup. The vulnerability is rated high severity with a CVSS score of 8.8.

References

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