CISA Known Exploited Vulnerability
This vulnerability is actively exploited in the wild and listed in the CISA Known Exploited Vulnerabilities catalog.
Remediation Deadline: Oct 28, 2025
Description
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.
EPSS — Exploit Probability
Higher than 96.1% of all CVEs
Required Action
https://wiki.zimbra.com/wiki/Security_Center ; https://nvd.nist.gov/vuln/detail/CVE-2025-27915
Risk Assessment
ELEVATEDDetails
- Severity
- High
- EPSS
- 24.9%
- CISA KEV
- Yes
- Ransomware
- Unknown
- Articles
- 1
Timeline
Published
Oct 7, 2025
Added to KEV
Oct 7, 2025
Remediation Due
Oct 28, 2025