CVE-2020-12846
CWE-434Published: June 3, 2020· Updated: Jun 17, 2026
Official Description
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.
Technical Analysis
CVE-2020-12846 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.0.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
Official Patches & Advisories
All References (6)
Quick Facts
Related CVEs (CWE-434)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2020-12846 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts