CVE-2026-33372: Synacor Zimbra Collaboration Suite

Medium severity, CVSS 5.4. EPSS: 0.2% chance of exploitation in the next 30 days.

An issue was discovered in Zimbra Collaboration (ZCS) 10.0 and 10.1. A cross-site request forgery (CSRF) vulnerability exists in Zimbra Webmail due to improper validation of CSRF tokens. The application accepts CSRF tokens supplied within the request body instead of requiring them through the expected request header. An attacker can exploit this issue by tricking an authenticated user into submitting a crafted request. This may allow unauthorized actions to be performed on behalf of the victim.

Affected products

• Synacor Zimbra Collaboration Suite: from 10.0.0, before 10.1.16 (fixed in 10.1.16)

Published 2026-03-20. Last modified 2026-06-17.