Synacor Zimbra Classic Web Client: Schwachstelle ermöglicht Cross-Site Scripting
WID-SEC-2026-2216 · first 07.07.2026 · updated 07.07.2026 · CVSS 8,1
What it is about
Zimbra ist eine Groupware-Lösung, die E-Mail, Kalender und Aufgabenverwaltung bietet. Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Synacor Zimbra Classic Web Client ausnutzen, um einen Cross-Site Scripting Angriff durchzuführen.
Under what conditions?
Over the network and without logging in. This is the most dangerous combination: attackers can scan reachable devices automatically.
What can happen in the worst case
An attacker could use the vulnerability to
- einen Cross-Site Scripting Angriff durchzuführen
Am I affected?
Affected according to the BSI:
- Synacor Zimbra Classic Web Client <10.1.19
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- Synacor Zimbra Classic Web Client 10.1.19
Is the vulnerability already being exploited?
None of the CVEs is in the CISA catalogue of exploited vulnerabilities. That does not mean there are no attacks, only that none are documented.
Information and sources
- Original BSI advisory (WID)
- Patch Release Update: Zimbra 10.1.19 vom 2026-07-06 blog.zimbra.com
- Zimbra Release Notes vom 2026-07-06 wiki.zimbra.com
Source: BSI warning and information service (CERT-Bund); CISA. The assessment of the conditions is my reading of the BSI text; the external pages are in their original language.