How severe is CVE-2023-37580?

CVE-2023-37580 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2023-37580?

Affected package information for CVE-2023-37580 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2023-37580?

No fixed version has been published for CVE-2023-37580 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2023-37580 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2023-37580, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2023-37580?

CVE-2023-37580 has an EPSS (Exploit Prediction Scoring System) score of 93.9%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2023-37580 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2023-37580 (Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2023-07-27. CISA required all US federal civilian agencies to remediate this vulnerability by 2023-08-17. The required action was: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2023-37580?

CVE-2023-37580 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Is there exploit tooling available for CVE-2023-37580?

A Nuclei detection template exists for CVE-2023-37580, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2023-37580 published, and has it been updated?

CVE-2023-37580 was published on July 31, 2023 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2023-07-27 — agencies required to remediate by 2023-08-17

CVE-2023-37580

MEDIUM

Published

Jul 31, 2023

Updated

Apr 10, 2026

Affected

0 pkgs

Patched

None yet

Exploits

2 known

EPSS Exploitation Probability

via FIRST.org ↗

93.9%probability of exploitation in next 30 days

Very High Risk100th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zi…

cisa.govCISAJul 2023

Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zi…

wiki.zimbra.comGoogle-sheetJun 2023

Frequently Asked Questions

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

O3 Security · Impact-Aware SCA

Is CVE-2023-37580 in your stack?

O3 detects CVE-2023-37580 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my stack How O3 SCA works