Vulnerability

CVE-2025-48700

Medium· 6.1KEVCVSS6.1EPSS18%

.rules3/5

Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability

Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that could allow attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information.

Threat signal

74/100

High

Severity

medium

CVSS

6.1

EPSS

18%

Active

KEV

CISA KEV — actively exploited

51d overdue

AffectedSynacor — Zimbra Collaboration Suite (ZCS)

Added to KEV

2026-04-20

Federal patch due (BOD 22-01)

2026-04-23

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 vulnerability that could allow attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information.”

CVSS

v3.1Open in FIRST calculator →

6.1/ 10MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 InteractionRequiredRequires user action (click, file open, etc).
ScopeChangedImpact extends beyond the vulnerable component (e.g. sandbox escape).
Confidentiality ImpactLowSome data disclosure; attacker doesn't fully control what.
Integrity ImpactLowSome data modification; attacker doesn't fully control extent.
Availability ImpactNoneNo availability impact.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

18.2%

probability of exploitation in next 30 days

p95

higher than 95% of all CVEs

3-day trend↑ 0pp

Above the FIRST 'patch on a priority schedule' threshold.

Vendor VEX

No VEX statements published for CVE-2025-48700. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAttend

Active exploitation with limited impact — coordinate patching

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

Lifecycle

2026-04-20Added to CISA KEVransomware: Unknown
2026-04-20Published
2026-04-23Federal 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.