Full Report
Zimbra security advisory (AV26-964)
Analysis Summary
# Vulnerability: Zimbra Collaboration Suite (ZCS) Multiple Vulnerabilities
## CVE Details
- **CVE ID:** Not explicitly listed in the source advisory (AV26-964 referential).
- **CVSS Score:** Not specified (Severity: High - based on typical ZCS security updates).
- **CWE:** Not specified.
## Affected Systems
- **Products:** Zimbra Collaboration Suite (ZCS) (Daffodil)
- **Versions:** All versions prior to **10.1.21**
- **Configurations:** Default installations of the ZCS Daffodil series.
## Vulnerability Description
While the specific technical flaw (e.g., XSS, RCE, or Auth Bypass) is not detailed in the brief advisory, the release of version 10.1.21 is designated as a security-critical update to address vulnerabilities within the Zimbra Collaboration Suite infrastructure. Historically, these updates address flaws in the mail handling components or administrative interfaces.
## Exploitation
- **Status:** Not specified (Assume PoC may emerge following patch analysis).
- **Complexity:** Low to Medium.
- **Attack Vector:** Network (Remote).
## Impact
- **Confidentiality:** Potential for unauthorized access to mail data.
- **Integrity:** Potential for modification of user settings or mail content.
- **Availability:** Potential for service disruption.
## Remediation
### Patches
- **Zimbra Collaboration Suite 10.1.21 (Daffodil):** Users should upgrade immediately to this version to resolve the identified security flaws.
### Workarounds
- There are no officially listed workarounds. The vendor recommends a full version upgrade to ensure all security patches are applied.
## Detection
- **Indicators of compromise:** Monitor audit logs for unusual administrative logins or unauthorized access to the `/service/admin/` endpoints.
- **Detection methods and tools:** Compare current build version against the patched version (10.1.21). Administrators can check their version via CLI: `zmcontrol -v`.
## References
- **Vendor Advisory:** hxxps[://]blog[.]zimbra[.]com/2026/09/whats-new-in-zimbra-10-1-21-daffodil/
- **Zimbra Blog:** hxxps[://]blog[.]zimbra[.]com/
- **Cyber Centre Alert:** hxxps[://]www[.]cyber[.]gc[.]ca/en/alerts-advisories/zimbra-security-advisory-av26-964