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?

Upgrade the affected component to the fixed release for CVE-2019-9621, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.

How do I detect CVE-2019-9621 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2019-9621 if there is no patch (or I can't update yet)?

Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

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 81.0%, 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 October 24, 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 · ACTIVELY EXPLOITED

HIGH severity

CVE-2019-9621 — zm-build

HIGH

CVE-2019-9621 is a high-severity (CVSS 7.5) Server-Side Request Forgery (SSRF) vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2025-07-07) — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.

Published

Apr 30, 2019

Updated

Oct 24, 2026

Affected

1 product

Patched

See advisory

Exploits

10 known

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2025-07-07. Federal agencies were required to remediate by 2025-07-28.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2019-9621.

EPSS Exploitation Probability

via FIRST.org ↗

81.0%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2019-9621 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Counts from FIRST.org, log-scaled.

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.

Affected Products

1 product · 48 configurations

Application

zimbra collaboration suitesynacor

≥ 8.8.0 && < 8.8.9

5 versions

8.6.08.7.118.8.98.8.108.8.11

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-46967webappsjsp

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

by k8gege · Jun 5, 2019

Exploit-DB Source

EDB-46693remotelinux✓ Verified

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

by Metasploit · Apr 12, 2019

Exploit-DB Source

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2019-9621, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

How to detect CVE-2019-9621

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2019-9621 -u https://target

Template: Zimbra Collaboration Suite - SSRF
Severity: high
Impact: Attackers can perform SSRF, potentially leading to internal network access or further exploitation.
Remediation: Update to the latest patched versions: 8.6 patch 13, 8.7.11 patch 10, 8.8.10 patch 7, or 8.8.11 patch 3 or later.

Template by ProjectDiscovery nuclei-templates (riteshs4hu), MIT licensed. View the full template. Scan only systems you are authorised to test.

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 dependencies?

Find it across , including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

7.5/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

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

Disclosed

Apr 30, 2019

First exploit

Jun 5, 2019

KEV added

Jul 7, 2025

Last updated

Oct 24, 2026

Identifiers

CVE-2019-9621

References

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

Related vulnerabilities

This CVE is high severity; 2 of 8 other CVEs with CWE-918 are rated as high or higher (top: critical).

CVE-2026-115886CVE-2026-62197CVE-2026-113671CVE-2026-111761CVE-2026-77524GHSA-p3pr-8f3m-4qp8CVE-2026-107394CVE-2026-60091Browse all CWE-918

Provenance

Sources

OSV.devNVDCISA KEVFIRST.org (EPSS)

Last verifiedOct 24, 2026

CVE-2019-9621 — zm-build

Exploitation Status

Actively exploited in the wild

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Description

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

How to detect CVE-2019-9621

Frequently Asked Questions

Is CVE-2019-9621 in your dependencies?