Vulnerability

CVE-2023-34192

Critical· 9.0KEVCVSS9EPSS90%

.rules3/5

Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting (XSS) vulnerability that allows a remote authenticated attacker to execute arbitrary code via a crafted script to the /h/autoSaveDraft function.

Threat signal

100/100

Severe

Severity

critical

CVSS

9.0

EPSS

90%

Active

KEV

CISA KEV — actively exploited

452d overdue

AffectedSynacor — Zimbra Collaboration Suite (ZCS)

Added to KEV

2025-02-25

Federal patch due (BOD 22-01)

2025-03-18

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 cross-site scripting (XSS) vulnerability that allows a remote authenticated attacker to execute arbitrary code via a crafted script to the /h/autoSaveDraft function.”

CVSS

v3.1Open in FIRST calculator →

9.0/ 10CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredLowStandard user privileges sufficient.
User InteractionRequiredRequires user action (click, file open, etc).
ScopeChangedImpact extends beyond the vulnerable component (e.g. sandbox escape).
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

89.6%

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-2023-34192. 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: yes
impact: total
mission: support

Lifecycle

2025-02-25Added to CISA KEVransomware: Unknown
2025-02-25Published
2025-03-18Federal 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.