CVE record
CVE-2025-27915
Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability
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.
CVE evidence
Known exploitation
Listed in CISA KEV
Absence from the fetched catalog does not establish that exploitation has not occurred.
Severity
moderate
CVSS 5.4 · CVSS_V3
Affected packages
0
Supported package records returned by OSV. Vendor and product names are not used to infer matches.
CISA Known Exploited Vulnerabilities
Catalog record
- Vendor / project
- Synacor
- Product
- Zimbra Collaboration Suite (ZCS)
- Date added
- Oct 7, 2025
- CISA federal remediation due date
- Oct 28, 2025
- Required action
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- Known ransomware campaign use
- Unknown
- CWE
- CWE-79
OSV package mapping