CVE-2020-12846: Synacor Zimbra Collaboration Suite

High severity, CVSS 8.0. EPSS: 2.6% chance of exploitation in the next 30 days.

Zimbra before 8.8.15 Patch 10 and 9.x before 9.0.0 Patch 3 allows remote code execution via an avatar file. There is potential abuse of /service/upload servlet in the webmail subsystem. A user can upload executable files (exe,sh,bat,jar) in the Contact section of the mailbox as an avatar image for a contact. A user will receive a "Corrupt File" error, but the file is still uploaded and stored locally in /opt/zimbra/data/tmp/upload/, leaving it open to possible remote execution.

Affected products

• Synacor Zimbra Collaboration Suite: before 8.8.15 (fixed in 8.8.15); version 8.8.15 only; version 9.0.0 only

Published 2020-06-03. Last modified 2026-06-17.