Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability (CVE-2025-48700)
Severity: medium · Patch status: unknown · Since 2026-04-20 · CVE-2025-48700
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. CISA added CVE-2025-48700 to its Known Exploited Vulnerabilities catalog on Apr 20, 2026, which means attackers are exploiting it in the wild.
What to do
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- US federal agencies must remediate by Apr 23, 2026 (BOD 22-01); treat that as the outer limit.
Sources
All live incidents on Threat Watch