Vulnerability record

CVE-2023-37580

Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

ElevatedExploitation confirmedCISA KEV

What should I do?

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Zimbra Collaboration Suite (ZCS), fix it now.

CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

US federal civilian agencies must remediate by Aug 17, 2023.

Patch status

Official fix available since Sep 30, 2026

Apply the vendor's update to every affected system. Check the fixed-in versions below where known.

Basis: NVD patch reference

Patch or advisory on openwall.com (opens in a new tab)

Description

Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.

Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.

Affected products

Products affected by this vulnerability, with versions and the source of each entry
Product	Vendor	Affected versions	Fixed in	Source
Zimbra Collaboration Suite	Synacor	>= 8.8.0, < 8.8.15; 8.8.15	8.8.15	NVD
Zimbra Collaboration Suite (ZCS)	Synacor	—	—	KEV

Sources: NVD = NIST National Vulnerability Database; KEV = CISA Known Exploited Vulnerabilities catalog.

Intelligence timeline

Developments from the last 30 days, newest first.

CVSS scoredUpdateKEVSep 30, 2026
CVE-2023-37580 scored CVSS 6.1: Synacor Zimbra Collaboration Suite (ZCS), Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability
CISA lists this as exploited in the wild. Unpatched Zimbra Collaboration Suite (ZCS) systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
Patch releasedUpdateKEVSep 30, 2026
Patch released for CVE-2023-37580: Synacor Zimbra Collaboration Suite (ZCS), Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability
An official fix is now available for Synacor Zimbra Collaboration Suite (ZCS). This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference

1 earlier event is available with a subscription. See plans.

Coverage

We have not published a story about this vulnerability yet.

References

wiki.zimbra.com https://wiki.zimbra.com/wiki/Security_Center
nvd.nist.gov https://nvd.nist.gov/vuln/detail/CVE-2023-37580
openwall.com http://www.openwall.com/lists/oss-security/2023/11/17/2
wiki.zimbra.com https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy
cisa.gov https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-37580