What’s Vulnerable › Vulnerabilities

CVE-2025-34403: MailEnable < 10.54 Reflected XSS in FieldTo Parameter of AddressBook.aspx

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-09 · updated 2026-10-14
• Weakness: CWE-79

Description

MailEnable versions prior to 10.54 contain a reflected cross-site scripting (XSS) vulnerability in the FieldTo parameter of /Mondo/lang/sys/Forms/AddressBook.aspx. The FieldTo value is not properly sanitized when processed via a GET request and is reflected inside a <script> block in the JavaScript variable var fieldTo. By supplying a crafted payload that terminates the existing Finish() function, inserts attacker-controlled script, and comments out remaining code, a remote attacker can execute arbitrary JavaScript in a victim’s browser when the victim attempts to send an email. Successful exploitation can redirect victims to malicious sites, steal non-HttpOnly cookies, inject arbitrary HTML or CSS, and perform actions as the authenticated user.

Affected products

• MailEnable: before 10.54 — fixed in 10.54

How to fix

Upgrade to a fixed version: MailEnable 10.54. Check the vendor advisory for mitigations.

References

• https://mailenable.com/Standard-ReleaseNotes.txt
• https://www.mailenable.com/
• https://www.vulncheck.com/advisories/mailenable-reflected-xss-in-fieldto-parameter-of-addressbook-aspx

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