Stored cross-site scripting in Zimbra Collaboration - CVE-2025-66376
Published: November 6, 2025 / Updated: March 18, 2026
Vulnerability identifier: #VU118165
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:A/U:Green
CVE-ID: CVE-2025-66376
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vendor: Synacor Inc.
Affected software:
Zimbra Collaboration
Zimbra Collaboration
Detailed vulnerability description
The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.
The vulnerability exists due to insufficient sanitization of user-supplied data. A remote attacker can inject and execute arbitrary HTML and script code in user's browser in context of vulnerable website.
Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.
How to mitigate CVE-2025-66376
Install updates from vendor's website.