Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability

Technical Severity

CVSS v3.1 Metrics

MEDIUM

6.1 / 10

Minimal Risk Critical

Vector Specification

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploitation Likelihood

EPSS Prediction

34.51 %

Predictive Probability

Percentile Rank

97.0 th

Documented as more likely to be exploited than 97.0% of known CVEs.

Detection Date

Apr 20, 2026

Remediation Due

Apr 23, 2026

CISA Catalog Active

Threat Analysis

Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that could allow attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information.

Remediation Directive

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

External Intelligence

https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories

NVD

National Vulnerability Database

https://nvd.nist.gov/vuln/detail/CVE-2025-48700