How severe is CVE-2019-9621?

CVE-2019-9621 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2019-9621?

Affected package information for CVE-2019-9621 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2019-9621?

No fixed version has been published for CVE-2019-9621 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-2019-9621 actively exploited in the wild?

Yes. There are 10 known exploit references for CVE-2019-9621, including 2 documented proof-of-concept exploits on Exploit-DB and 7 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-2019-9621?

CVE-2019-9621 has an EPSS (Exploit Prediction Scoring System) score of 94.1%, 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-2019-9621 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2019-9621 (Synacor Zimbra Collaboration Suite (ZCS) Server-Side Request Forgery (SSRF) Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2025-07-07. CISA required all US federal civilian agencies to remediate this vulnerability by 2025-07-28. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, 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-2019-9621?

CVE-2019-9621 is classified as Server-Side Request Forgery (SSRF) (CWE-918). 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-2019-9621?

A Nuclei detection template exists for CVE-2019-9621, 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-2019-9621 published, and has it been updated?

CVE-2019-9621 was published on April 30, 2019 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 2025-07-07 — agencies required to remediate by 2025-07-28

CVE-2019-9621

HIGH

Published

Apr 30, 2019

Updated

Apr 10, 2026

Affected

0 pkgs

Patched

None yet

Exploits

10 known

EPSS Exploitation Probability

via FIRST.org ↗

94.1%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 Suite before 8.6 patch 13, 8.7.x before 8.7.11 patch 10, and 8.8.x before 8.8.10 patch 7 or 8.8.x before 8.8.11 patch 3 allows SSRF via the ProxyServlet component.

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.

EDB-46693remotelinux✓ Verified

Zimbra Collaboration - Autodiscover Servlet XXE and ProxyServlet SSRF (Metasploit)

by Metasploit · Apr 12, 2019

Exploit-DB Source

EDB-46967webappsjsp

Zimbra < 8.8.11 - XML External Entity Injection / Server-Side Request Forgery

by k8gege · Jun 5, 2019

Exploit-DB Source

Frequently Asked Questions

Zimbra Collaboration Suite before 8.6 patch 13, 8.7.x before 8.7.11 patch 10, and 8.8.x before 8.8.10 patch 7 or 8.8.x before 8.8.11 patch 3 allows SSRF via the ProxyServlet component.

O3 Security · Impact-Aware SCA

Is CVE-2019-9621 in your stack?

O3 detects CVE-2019-9621 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

CVSS Score

7.5/10

CVSS v3 base score

Vector breakdown

AV:Attack Vector

Network

AC:Attack Complexity

Low

PR:Privileges Required

None

UI:User Interaction

None

S:Scope

Unchanged

C:Confidentiality

High

I:Integrity

None

A:Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CWE Classification

CWE-918Server-Side Request Forgery (SSRF)

Weaponization

Timeline

First exploit

Apr 12, 2019

Disclosed

Apr 30, 2019

KEV added

Jul 7, 2025

Last updated

Apr 10, 2026

Identifiers

CVE-2019-9621

References

Advisoryblog.zimbra.com Advisorywiki.zimbra.com Advisoryblog.tint0.com Advisorywiki.zimbra.com Reportbugzilla.zimbra.com Webcisa.gov Evidencerapid7.com Evidencepacketstormsecurity.com Evidencepacketstormsecurity.com Evidenceexploit-db.com

Data from OSV.dev, enriched by O3 Security. Refreshed hourly.