CVE-2025-27915
Description
An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a <details> tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.
Summary dbcve.org
A stored cross-site scripting (XSS) vulnerability in Zimbra Collaboration versions 9.0, 10.0, and 10.1 allows attackers to inject malicious JavaScript via ICS (iCalendar) file content embedded in emails. The Classic Web Client fails to properly sanitize HTML in ICS entries, enabling execution of arbitrary JavaScript through an ontoggle event within a <details> tag when the user views the crafted message.
Mitigation
Upgrade ZCS to a patched version that properly sanitizes ICS file content, or implement input validation to strip dangerous HTML/JS from ICS attachments before rendering in the Classic Web Client.