What is CVE-2023-37580?

CVE-2023-37580 is a medium-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2023-07-31.

How severe is CVE-2023-37580?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2023-37580 known to be exploited?

Yes. CVE-2023-37580 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-07-27), indicating it is being actively exploited. 3 public proof-of-concept repositories are indexed.

XSS in Synacor Zimbra Collaboration Suite

CVE-2023-37580

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

Vulnerability class: XSS (Cross-Site Scripting)

Published 2023-07-31 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.491 (98.9th percentile), scored 2026-10-18.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.467 · newest: 0.491 · change: +0.024

Affected products

Synacor Zimbra Collaboration Suite — versions 8.8.15

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2023-07-27. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2023-08-17.

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

Public proof-of-concept exploits

References

wiki.zimbra.com/wiki/Security_Center (Release Notes)
wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy (Not Applicable)
www.openwall.com/lists/oss-security/2023/11/17/2 (mailing-list, Patch, Mailing List)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2023-37580?: CVE-2023-37580 is a medium-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2023-07-31.
How severe is CVE-2023-37580?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2023-37580 known to be exploited?: Yes. CVE-2023-37580 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-07-27), indicating it is being actively exploited. 3 public proof-of-concept repositories are indexed.