CVE-2019-9621
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.
do firstApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Can a WAF block it? Partly. The vulnerability is a server-side request forgery via the ProxyServlet component, which is accessed through HTTP requests. Such requests may contain unusual internal URLs or parameters that a WAF could partially detect, but some legitimate proxy requests might look similar. A custom WAF rule can filter requests to ProxyServlet with unusual internal URL patterns, but attackers can vary the request. No tracked WAF vendor has published a rule for this CVE yet.
What a custom rule would match: requests to ProxyServlet with unusual internal URL patterns
Also consider: patch · custom WAF rule · egress filter · IMDSv2
Based on an AI reading of the CVE description, and no vendor rule found yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2019-9621 being exploited?
Yes. CVE-2019-9621 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2019-9621?
CVE-2019-9621 is rated High with a CVSS score of 7.5. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2019-9621?
Yes. A fix has been recorded for CVE-2019-9621. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2019-9621 affect?
CVE-2019-9621 affects synacor:zimbra_collaboration_suite. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
public exploits
Public exploit code: 6 on Exploit-DB · 1 Metasploit module · 1 GitHub proof of concept · 1 Nuclei template
- Zimbra < 8.8.11 - XML External Entity Injection / Server-Side Request Forgery · webapps · 5 Jun 2019
- Zimbra < 8.8.11 - XML External Entity Injection / Server-Side Request Forgery · webapps · 5 Jun 2019
- Zimbra Collaboration - Autodiscover Servlet XXE and ProxyServlet SSRF (Metasploit) · remote · 12 Apr 2019 · verified
- Zimbra Collaboration - Autodiscover Servlet XXE and ProxyServlet SSRF (Metasploit) · remote · 12 Apr 2019 · verified
- exploit/linux/http/zimbra_xxe_rce · exploit · excellent
- Zimbra Collaboration Suite - SSRF · detection template · high
- k8gege/ZimbraExploit · 78 ★
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
cisa ssvc
- exploitation
- active
- automatable
- yes
- technical impact
- partial
Assessed by CISA 17 Jul 2025 (SSVC 2.0.3).
timeline
- 12 Apr 2019First public exploit or proof of concept
- 30 Apr 2019Published · 19 days later
- 7 Jul 2025Added to CISA KEV (exploited in the wild) · 2,259 days (about 6 years) later
- 17 Jul 2025CISA SSVC assessment: exploitation active · 10 days later
- 28 Jul 2025CISA remediation due date (US federal agencies) · 11 days later
- 21 Oct 2025CVE record last updated · 86 days (about 3 months) later
- 2 Nov 2026Analysed by vulneraibility.com · 377 days (about 1 year) later
- Exploitexploit-db.com /exploits/46693/
- Linkwiki.zimbra.com /wiki/Zimbra_Security_Advisories
- Linkwiki.zimbra.com /wiki/Security_Center
- Linkbugzilla.zimbra.com /show_bug.cgi?id=109127
- Linkrapid7.com /db/modules/exploit/linux/http/zimbra_xxe_rce
- Linkpacketstormsecurity.com /files/152487/Zimbra-Collaboration-Autodiscover-Servlet-XXE-ProxyServlet-SSRF.ht
- Linkblog.zimbra.com /2019/03/9826/
- Linkblog.tint0.com /2019/03/a-saga-of-code-executions-on-zimbra.html
Show 2 more
- Linkpacketstormsecurity.com /files/153190/Zimbra-XML-Injection-Server-Side-Request-Forgery.html
- Linkcisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-9621
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Exploit-DB: published exploits
- Metasploit Framework: exploit and scanner modules
- Nuclei templates: detection templates
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.