Vendor

Synacor

0 mentions in 7 days · 2 in 30 days · 2 total · first seen Aug 21, 2026 · last 22d ago

Timeline2 articles

Unpatched Zimbra servers are falling to CVE-2026-73570 attacks

Attackers are exploiting unpatched Zimbra servers via CVE-2026-73570; 274 instances compromised, and CISA added the flaw to its KEV catalog.

The Shadowserver Foundation counted at least 274 compromised internet-facing Zimbra Collaboration Suite instances exploited through CVE-2026-73570, up from 155 on August 20. The unauthenticated code injection flaw affects servers with the optional zimbra-snmp package and SNMP notifications enabled, allowing arbitrary OS command execution via crafted SMTP requests. Synacor patched the issue in ZCS v10.1.20 on July 20, 2026, and at least 8,200 instances remain unpatched. CISA added the flaw to its Known Exploited Vulnerabilities catalog and gave US federal civilian agencies three days to remediate and check for compromise.

Help Net SecurityAug 25, 00:00 UTC · 22d agoExploit / PoC in the wildCVE-2026-735701

Poland's CERT Warns of Active Exploitation of Critical Zimbra Collaboration Suite Flaw

CERT Polska confirms active exploitation of critical unauthenticated RCE CVE-2026-73570 in Zimbra Collaboration Suite, patched July 20.

CERT Polska confirmed threat actors are actively exploiting CVE-2026-73570, an unauthenticated OS command injection in Zimbra Collaboration Suite allowing arbitrary shell commands as the zimbra user. Exploitation requires the SNMP trap service via snmp_notify with swatchdog running, which is enabled by default; Shadowserver tracks over 12,100 internet-exposed Zimbra servers. Zimbra fixed the flaw in version 10.1.20 on July 20, 2026, 28 days before exploitation was confirmed. Historical Zimbra targeting includes Winter Vivern, APT29, and APT28 campaigns.

Security AffairsAug 21, 09:14 UTC · 25d agoExploit / PoC in the wildCVE-2026-73570

Related CVEsby mentions

CVE-2026-735708.932%
Unauthenticated OS Command Injection RCE in Synacor Zimbra Collaboration Suite
CVE-2026-73570 is an OS command injection vulnerability (CWE-78) in Synacor Zimbra Collaboration Suite (ZCS) before 10.1.20, caused by improper sanitization of untrusted input during SNMP notification processing. It is triggered when the optional zimbra-snmp package is installed and SNMP notifications are enabled: an unauthenticated attacker sends specially crafted SMTP requests that the flawed notification path turns into execution of arbitrary operating system commands. Successful exploitation runs commands as the Zimbra user, giving attackers control of the mail server's service account with high confidentiality and integrity impact across the host. Only ZCS deployments running the optional SNMP component with notifications enabled are vulnerable; other Zimbra installs are not exposed to this specific flaw. The flaw is under active exploitation: CISA added it to the KEV catalog on 2026-08-21, Poland's CERT has warned of in-the-wild attacks, unpatched Zimbra servers are reported compromised, and two public proof-of-concept exploits exist.
· Synacor Zimbra Collaboration Suite (ZCS) before 10.1.20 (when the optional zimbra-snmp package is installed and SNMP notifications are enabled) KEV PoC ×4large

Appears with

product Zimbra Collaboration Suite 2 vendor Zimbra 2 threat actor Winter Vivern 1 organization CERT Polska 1 organization CISA 1 threat actor APT28 1 organization Seqrite Labs 1 organization Shadowserver 1 organization Shadowserver Foundation 1 organization Polish CERT 1 threat actor APT29 1

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