Vulnerability

CVE-2019-9621

High· 7.5KEVEXPLOITCVSS7.5EPSS94%

.rules3/5

Synacor Zimbra Collaboration Suite (ZCS) Server-Side Request Forgery (SSRF) Vulnerability

Synacor Zimbra Collaboration Suite (ZCS) contains a server-side request forgery (SSRF) vulnerability via the ProxyServlet component.

Threat signal

100/100

Severe

Severity

high

CVSS

7.5

EPSS

94%

Active

KEV

CISA KEV — actively exploited

320d overdue

AffectedSynacor — Zimbra Collaboration Suite (ZCS)

Added to KEV

2025-07-07

Federal patch due (BOD 22-01)

2025-07-28

Required action (CISA verbatim)

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisory + references

CISA description: “Synacor Zimbra Collaboration Suite (ZCS) contains a server-side request forgery (SSRF) vulnerability via the ProxyServlet component.”

CVSS

v3.1Open in FIRST calculator →

7.5/ 10HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionNoneFully automated — no victim action needed.
ScopeUnchangedImpact contained to the vulnerable component.
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactNoneNo integrity impact.
Availability ImpactNoneNo availability impact.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

94.1%

probability of exploitation in next 30 days

p100

higher than 100% of all CVEs

3-day trend↑ 0pp

Statistically about to be weaponized — top-tier triage urgency.

Vendor VEX

No VEX statements published for CVE-2019-9621. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAct

Active exploitation with total impact on essential/support systems

exploitation: active
automatable: no
impact: total
mission: support

Lifecycle

2025-07-07Added to CISA KEVransomware: Unknown
2025-07-07Public exploit observedexploitdb, metasploit
2025-07-07Published
2025-07-28Federal patch due (BOD 22-01)
2026-06-12Last modified1 source

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.