CVE-2026-73570
Zimbra Collaboration Suite (ZCS) OS Command Injection in Synacor Zimbra Collaboration Suite (ZCS). CISA confirmed attackers exploit it and added it to its Known Exploited Vulnerabilities catalog on 21 August 2026.
- Product
- Synacor Zimbra Collaboration Suite (ZCS)
- Added to CISA's catalog
- Federal fix-by date
- Ransomware
- No known use in ransomware campaigns
- Vendor advisories
- Sources
- CISA’s catalog, NVD entry
CISA’s description.
Zimbra Collaboration Suite (ZCS) contains an OS command injection vulnerability which could allow an unauthenticated attacker to send specially crafted SMTP requests that may result in execution of arbitrary operating system commands as the Zimbra user.
More from Synacor this year.
- CVE-2025-48700 Cross-site Scripting, added
- CVE-2025-66376 Cross-Site Scripting, added
- CVE-2020-7796 (ZCS) Server-Side Request Forgery, added
- CVE-2025-68645 PHP Remote File Inclusion, added
Every flaw CISA confirmed exploited in the last 30 days is on the exploit watch. This is not security advice. Check the vendor’s advisory before acting. From CISA’s catalog of 4 November 2026.