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CVE-2019-9621: Synacor Zimbra Collaboration Suite (ZCS) Server-Side Request Forgery (SSRF) Vulnerability

criticalknown exploitedpublic exploitCVE-2019-9621
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
Synacor Zimbra Collaboration Suite (ZCS) contains a server-side request forgery (SSRF) vulnerability via the ProxyServlet component.

CSIRTS triage

vendor: Synacorproduct: Zimbra Collaboration Suite (ZCS)Server-side request forgery
What
Zimbra Collaboration Suite (ZCS) contains a server-side request forgery (SSRF) vulnerability via the ProxyServlet component.
Who is affected
Deployments of Zimbra Collaboration Suite (ZCS) are at risk of exploitation.
Urgency
This is a critical vulnerability with confirmed exploitation, requiring immediate remediation.
Action
Apply the latest security updates from Synacor to address this vulnerability.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source
CISA Known Exploited Vulnerabilities (US · database · site)
Severity
critical
Published
2025-07-07
Exploitation
Observed in the wild (CISA KEV)

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2019-9621

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2019-9621coverage & exploitation statusNVD · CVE.org

Recent advisories for Synacor Zimbra Collaboration

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

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