CVE-2026-23606 GFI MailEssentials AI < 22.4 Advanced Content Filtering Rule Stored XSS

What is CVE-2026-23606?

CVE-2026-23606 is a medium-severity cross-site scripting vulnerability in GFI Software MailEssentials AI, published on 19 Feb 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

GFI MailEssentials AI versions prior to 22.4 contain a stored cross-site scripting vulnerability in the Advanced Content Filtering rule creation workflow. An authenticated user can supply HTML/JavaScript in the ctl00$ContentPlaceHolder1$pv1$txtRuleName parameter to /MailEssentials/pages/MailSecurity/advancedfiltering.aspx, which is stored and later rendered in the management interface, allowing script execution in the context of a logged-in user.

Weakness: CWE-79

Which versions are affected by CVE-2026-23606?

It affects 1 product.

Products include Gfi Mailessentials.

How do I fix CVE-2026-23606?

No fix has been published for CVE-2026-23606 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-23606 being exploited?

There is no known exploitation of CVE-2026-23606 in the wild and no public exploit code.

Other vulnerabilities in GFI Software MailEssentials AI

• CVE-2004-1312 Denial of service in n/a Critical 10.0
• CVE-2025-34491 GFI MailEssentials < 21.8 MultiNode Insecure Deserialization High 8.8
• CVE-2025-34489 GFI MailEssentials < 21.8 Local Privilege Escalation High 7.8
• CVE-2025-34490 GFI MailEssentials < 21.8 XXE Arbitrary File Read Medium 6.5
• CVE-2026-23620 GFI MailEssentials AI < 22.4 ListServer.IsDBExist() Absolute Directory Traversal to File Enumeration Medium 5.3

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-xwc9-vwhh-qfwc.