Unauthenticated command injection on internet-facing mail servers: tracking CVE-2026-73570
Microsoft Threat Intelligence examines CVE-2026-73570 exploitation in Zimbra, including observed attack paths, detection opportunities, and mitigation guidance.
Excerpt from the primary source: Microsoft Security Blog & MSRC
Who is affected
Developers · Security professionals
Affected technology: Zimbra Collaboration Suite (ZCS)
Why it matters
CISA lists this as exploited in the wild. Unpatched Zimbra Collaboration Suite (ZCS) systems are exposed to active attacks now.
Automated: stated only from CISA listings and the exploitation evidence in the sources below.
What you should do · Patch
Apply the vendor's security update for Zimbra Collaboration Suite (ZCS). Check the linked advisory for affected and fixed versions, and put internet-facing systems first.
CISA's required action for CVE-2026-73570: "Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines." US federal civilian agencies must comply by August 24, 2026.
Automated guidance based on this story's classification. Check the linked advisories for specifics.
Sources
We link to original and authoritative sources. Headlines and excerpts belong to their publishers.
Vendor advisory
Original reporting
Additional reporting
Related
US, Australia warn of latest Citrix vulnerability after NetScaler advisory
Citrix confirmed late on Friday that it was “tracking a newly observed issue” related to some customer-managed NetScaler deployments but claimed the problem was not connected to vulnerabilities reported last week that also caused alarm among cybersecurity experts.
New Dell System Update flaw lets hackers gain root privileges
Dell warned customers to patch a critical vulnerability in the System Update (DSU) command-line interface (CLI) deployment tool as soon as possible.
Apply the vendor's security update for the affected products.
Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability (CVE-2026-88779) is being actively exploited, CISA warns
CISA added CVE-2026-88779 (Citrix NetScaler) to its Known Exploited Vulnerabilities catalog on October 4, 2026, which means there is reliable evidence of exploitation in the wild. Citrix NetScaler ADC (formerly Citrix ADC) and Citrix NetScaler Gateway (formerly Citrix Gateway) contain an improper restriction of operations within the bounds of a memory buffer vulnerability that could allow for a denial of service.
CISA lists this as exploited in the wild. Unpatched NetScaler ADC / Gateway systems are exposed to active attacks now.
Treat this as an emergency.
Fortra Patches Critical Vulnerabilities in BoKS
The bugs could lead to authentication bypass, shell command execution, and memory corruption.
Apply the vendor's security update for the affected products.