CVE-2025-27915 - Synacor Zimbra Collaboration Suite (ZCS)
AI Vulnerability ContextAn 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 Java...
Overview
A source-backed snapshot of this vulnerability.
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.
Vulnerability status
How serious this vulnerability is and whether it is known to be exploited.
- CVE ID
- CVE-2025-27915
- Vendor/project
- Synacor
- Product
- Zimbra Collaboration Suite (ZCS)
- Vulnerability name
- Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
- Date added
- 2025-10-07
- Due date
- 2025-10-28
- Known ransomware campaign use
- Unknown
- CVSS v3
- 5.4
Exploit context
What the vulnerability is about.
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.
Source evidence
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Original source
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