CVE-2025-34491 GFI MailEssentials < 21.8 MultiNode Insecure Deserialization
Authenticated attackers can execute arbitrary code via insecure .NET deserialization in GFI MailEssentials Multi-Server setups.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-34491?
CVE-2025-34491 is a high-severity unsafe deserialization vulnerability in GFI MailEssentials, published on 28 Apr 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-502
Which versions are affected by CVE-2025-34491?
It affects 1 product.
Products include Gfi Mailessentials.
How do I fix CVE-2025-34491?
No fix has been published for CVE-2025-34491 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2025-34491 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-34491 exists.
Other vulnerabilities in GFI MailEssentials
- CVE-2004-1312 Denial of service in n/a
- CVE-2025-34489 GFI MailEssentials < 21.8 Local Privilege Escalation
- CVE-2025-34490 GFI MailEssentials < 21.8 XXE Arbitrary File Read
- CVE-2026-23620 GFI MailEssentials AI < 22.4 ListServer.IsDBExist() Absolute Directory Traversal to File Enumeration
- CVE-2026-23621 GFI MailEssentials AI < 22.4 ListServer.IsPathExist() Absolute Directory Traversal to File Enumeration
Sources
Also known as GHSA-fqqj-qgxm-vg3x.