How severe is CVE-2020-12846?

CVE-2020-12846 has a CVSS 3.x base score of 8.0, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-12846 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-12846?

CVE-2020-12846 primarily affects Synacor Zimbra Collaboration Suite. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-12846?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-12846 published?

CVE-2020-12846 was published on 2020-06-03 and last updated on 2026-06-17.

CVE-2020-12846

CVE-2020-12846 is a high-severity vulnerability in Synacor Zimbra Collaboration Suite with a CVSS 3.x base score of 8.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-434.

Key facts

Severity: High (CVSS 3.x base score 8.0)
CVSS v2: 6.0
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Synacor Zimbra Collaboration Suite
Published: 2020-06-03
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2020-12846?: 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.
How severe is CVE-2020-12846?: CVE-2020-12846 has a CVSS 3.x base score of 8.0, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-12846 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-12846?: CVE-2020-12846 primarily affects Synacor Zimbra Collaboration Suite. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-12846?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-12846 published?: CVE-2020-12846 was published on 2020-06-03 and last updated on 2026-06-17.

References

Affected products (14)

cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:-:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p1:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p2:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p3:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p4:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p5:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p6:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p7:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p8:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p9:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:-:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p1:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p2:*:*:*:*:*:*

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