Vulnerability

CVE-2025-6543

Critical· 9.8KEVCVSS9.8EPSS1%

.rules3/5

Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability

Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

Threat signal

100/100

Severe

Severity

critical

CVSS

9.8

EPSS

Active

KEV

CISA KEV — actively exploited

327d overdue

AffectedCitrix — NetScaler ADC and Gateway

Added to KEV

2025-06-30

Federal patch due (BOD 22-01)

2025-07-21

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: “Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.”

CVSS

v3.1Open in FIRST calculator →

9.8/ 10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

1.06%

probability of exploitation in next 30 days

p78

higher than 78% of all CVEs

3-day trend↑ 0pp

Mid-pack — moderate exploitation likelihood.

Vendor VEX

No VEX statements published for CVE-2025-6543. 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

2025-06-30Added to CISA KEVransomware: Unknown
2025-06-30Published
2025-07-21Federal patch due (BOD 22-01)
2026-06-12Last modified1 source

Mentions in news & research

research:wizCritical vulnerabilities in NetScaler ADC exploited in-the-wild: everything you need to know2025-07-06

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