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.
- Vendor
- Citrix
- Product
- NetScaler ADC and Gateway
- CVSS
- 9.8
- EPSS (exploit probability)
- 10.4%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2025-6543 being exploited?
Yes. CISA added CVE-2025-6543 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild. It is also listed in ENISA's EU Vulnerability Database (EUVD) exploited list.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 10.4% (scored October 25, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ LISTED ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-11-13. Full cross-catalog view: /kev-comparison
CVE-2025-6543 timeline
Every event links to its source. Catalog dates are each catalog's own; day offsets count from NVD publication. Data: JSON
What to do
CISA required actionApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
US federal civilian agencies must remediate by (21 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Citrix NetScaler ADC and NetScaler Gateway CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2026-107406 Memory overflow in Citrix NetScaler ADC and Gateway SAML handlingwrite-up | [ CRITICAL ] | 9.5 | 1.9% | — |
| CVE-2026-88779 Citrix NetScaler Memory Buffer Flaw Enables Denial-of-Service Attackswrite-up | [ HIGH ] | 7.5 | 11.4% | |
| CVE-2026-88772 Citrix NetScaler ADC/Gateway RCE via Memory Buffer Mishandlingwrite-up | [ HIGH ] | — | 76.6% | |
| CVE-2026-88771 Citrix NetScaler ADC/Gateway Unauthenticated RCE via Input Validation Flawwrite-up | [ HIGH ] | — | 81.9% | |
| CVE-2026-19490 Critical authentication bypass in Citrix NetScaler ADC and Gatewaywrite-up | [ CRITICAL ] | 9.3 | 33.3% | |
| CVE-2026-8452 Citrix NetScaler ADC and Gateway Memory Buffer Overflowwrite-up | [ CRITICAL ] | 9.8 | 1.0% | |
| CVE-2025-5777 Citrix Bleed 2 — NetScaler ADC/Gateway memory-disclosure leaking session tokensransomware usewrite-up | [ HIGH ] | 7.5 | 100.0% | |
| CVE-2023-6549 Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability | [ HIGH ] | 8.2 | 57.6% |