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.
Impersonating IT support: how threat actors turn a remote session into enterprise-wide access
Microsoft details Teams IT-support impersonation campaigns deploying Node.js implants, AD reconnaissance, and WinRM lateral movement toward domain controllers.
Microsoft Threat Intelligence describes a human-operated campaign where attackers impersonate IT/helpdesk staff via Microsoft Teams external collaboration, talk users into granting remote sessions, and use RMM tools for interactive access. During the session they run PowerShell to silently install a malicious MSI that stages a portable Node.js runtime and obfuscated JavaScript implant for C2, executing follow-on payloads via rundll32. Operators then perform host and Active Directory reconnaissance, capture desktop screenshots, and pivot via WinRM on port 5985 to domain controllers and certificate authorities. The hands-on-keyboard chain, which can precede data theft and ransomware, blends into normal operations by relying on Teams, Quick Assist, msiexec, and Node.js; Microsoft shares hunting and mitigation guidance.
U.S. CISA adds Zimbra Collaboration Suite (ZCS) flaw to its Known Exploited Vulnerabilities catalog
CISA added actively exploited Zimbra flaw CVE-2026-73570 (unauthenticated OS command injection RCE) to its KEV catalog, setting an August 24, 2026 federal patch deadline.
CISA added CVE-2026-73570, an unauthenticated OS command injection flaw in Zimbra Collaboration Suite, to its Known Exploited Vulnerabilities catalog after CERT Polska confirmed active exploitation. The flaw lets attackers execute shell commands as the zimbra user via the snmp_notify parameter when the SNMP trap service is enabled and the default swatchdog service is running. Zimbra patched the issue in version 10.1.20 released July 20, 2026, 28 days before exploitation was confirmed. Under BOD 22-01, federal civilian agencies must patch by August 24, 2026.
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.
⚡ Weekly Recap: VMware Exploits, Windows 0-Day, MCP Attacks, Browser Hijacks and More
Weekly recap: suspected China-nexus APT exploited VMware vCenter CVE-2026-59310, Lazarus used Windows zero-day CVE-2026-68820, and macOS flaw dropped Monero miners.
The week's top stories included a suspected China-nexus APT exploiting VMware vCenter CVE-2026-59310 (CVSS 9.8), a directory-traversal flaw enabling arbitrary code execution, with backdoors, reverse SSH and Babuk-derived ransomware deployed, per QUIRSO. NCSC-NL reported active exploitation of macOS Screen Sharing flaw CVE-2026-65400 (CVSS 9.8) to install Monero miners on systems with port 5900 exposed. Lazarus Group exploited Windows zero-day CVE-2026-68820 (CVSS 7.0) in Operation Dream Job, delivering ForestTiger and Troy backdoors to defense and aerospace targets. GeoServer patched a critical SQL injection flaw exploited within hours of disclosure, and Jamf analyzed the new Amnesia Stealer for macOS with live browser control.