MEDIUM 5.3 NVD
CVE-2026-66912
Zimbra is vulnerable to Stored Cross-Site Scripting (XSS) via the From email header during HTML reply composition in Classic UI. Due to insufficient sanitizatio
Zimbra is vulnerable to Stored Cross-Site Scripting (XSS) via the From email header during HTML reply composition in Classic UI. Due to insufficient sanitization of the From header value, a remote attacker can send a crafted email containing a malicious From header with an embedded JavaScript payload. When the victim opens the message in Classic UI and clicks Reply while composing in HTML mode with reply headers disabled, the unsanitized From header content is rendered as HTML and the JavaScript payload executes in the victim's browser, potentially allowing the attacker to steal session information or perform actions on behalf of the victim. This issue was fixed in version 10.1.21
References
- https://cert.pl/en/posts/2026/10/CVE-2026-66911
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
This medium severity vulnerability with a CVSS score of 5.3 was published on 2026-10-29 via NVD.
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