CVE-2025-27915
Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
Summary
Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that 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 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.
Affected software
Vendor: Synacor · Product: Zimbra Collaboration Suite (ZCS)
Weakness types (CWE):
What to do
This vulnerability appears in CISA's Known Exploited Vulnerabilities catalog, meaning it is being exploited in the wild. Prioritize patching affected systems and verify exposure across your estate.
Related vulnerabilities in Synacor
| CVE | Name | EPSS | Exploited |
|---|---|---|---|
| CVE-2019-9670 | Synacor Zimbra Collaboration Suite (ZCS) Improper Restriction of XML External En | 100.0% | Yes |
| CVE-2024-45519 | Synacor Zimbra Collaboration Suite (ZCS) Command Execution Vulnerability | 99.9% | Yes |
| CVE-2022-27925 | Synacor Zimbra Collaboration Suite (ZCS) Arbitrary File Upload Vulnerability | 98.7% | Yes |
| CVE-2022-41352 | Synacor Zimbra Collaboration Suite (ZCS) Arbitrary File Upload Vulnerability | 95.5% | Yes |
| CVE-2022-27924 | Synacor Zimbra Collaboration Suite (ZCS) Command Injection Vulnerability | 93.9% | Yes |
| CVE-2020-7796 | Synacor Zimbra Collaboration Suite (ZCS) Server-Side Request Forgery Vulnerabili | 93.6% | Yes |
| CVE-2022-37042 | Synacor Zimbra Collaboration Suite (ZCS) Authentication Bypass Vulnerability | 92.1% | Yes |
| CVE-2019-9621 | Synacor Zimbra Collaboration Suite (ZCS) Server-Side Request Forgery (SSRF) Vuln | 81.0% | Yes |
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