Product

Zimbra Collaboration

0 mentions in 7 days · 1 in 30 days · 1 total · first seen Aug 26, 2026 · last 21d ago

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Attackers Exploit Zimbra SNMP Flaw for Unauthenticated Remote Code Execution

CERT Polska and CISA report active exploitation of Zimbra RCE CVE-2026-73570, with 267 instances compromised per Shadowserver.

CVE-2026-73570 (CVSS 8.9) enables unauthenticated command injection and remote code execution in Zimbra Collaboration before 10.1.20 when the optional zimbra-snmp package is installed and SNMP notifications are enabled, via crafted SMTP requests. CISA added the flaw to its KEV catalog on August 21, 2026, with a federal patch deadline of August 24. The Shadowserver Foundation counted 267 compromised instances as of August 24, 2026, led by the US (46), Sweden (21), France (20) and Germany (17). Separately, Russia-linked Laundry Bear has weaponized Zimbra stored XSS CVE-2025-66376 against Western government and commercial mail servers since at least July 2025, delivering the ZimReaper payload.

The Hacker NewsAug 26, 05:08 UTC · 21d agoExploit / PoC in the wildCVE-2026-73570 CVE-2025-663761

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
CVE-2025-663766.120%
Stored Cross-Site Scripting in Synacor Zimbra Collaboration Suite Classic UI
Zimbra Collaboration Suite (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 is vulnerable to stored cross-site scripting through its Classic webmail interface. An attacker sends an HTML e-mail containing a Cascading Style Sheets (CSS) @import directive, and when a recipient opens that message in Classic UI, the injected content executes as script in the victim's browser session. Successful exploitation lets an attacker run arbitrary JavaScript in the Zimbra webmail context, potentially hijacking the session, reading mail, or acting as the user, consistent with the cross-scope impact reflected in the 6.1 CVSS score. Only deployments running the affected ZCS 10/10.1 versions with the Classic UI enabled are exposed; organizations on patched releases or not using Classic UI are not impacted. CISA added the flaw to the Known Exploited Vulnerabilities catalog on 2026-03-18, confirming exploitation in the wild, and recent reporting describes Zimbra flaws being used by Russian-aligned espionage actors against Western and Ukrainian targets.
· Synacor Zimbra Collaboration Suite (ZCS) 10 10.x before 10.0.18 · Synacor Zimbra Collaboration Suite (ZCS) 10.1 10.1.x before 10.1.13 KEVlarge

Appears with

threat actor Laundry Bear 1 malware ZimReaper 1 organization CERT Polska 1 organization CISA 1 organization Shadowserver Foundation 1 vendor CERT Polska 1 vendor CISA 1 vendor Shadowserver Foundation 1 vendor Zimbra 1

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