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.
CISA Known Exploited Vulnerability
Date added 2025-10-07 | Due date 2025-10-28
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
References
strikeready.com/blog/0day-ics-attack-in-the-wild/
www.cisa.gov/...erabilities-catalog?field_cve=CVE-2025-27915
wiki.zimbra.com/wiki/Security_Center
wiki.zimbra.com/wiki/Zimbra_Releases/10.1.5
wiki.zimbra.com/wiki/Zimbra_Releases/10.0.13
