XSS in Synacor Zimbra_collaboration_suite

CVE-2025-27915

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 view…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.043 (90.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

Affected products

Weakness classification (CWE)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: .

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.

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-27915?
CVE-2025-27915 is a medium-severity vulnerability in Synacor Zimbra_collaboration_suite, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2025-03-12.
How severe is CVE-2025-27915?
Medium severity. CVSS v3 base score is 5.4 out of 10.
Is CVE-2025-27915 known to be exploited?
Yes. CVE-2025-27915 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-10-07), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.