CVE-2025-6543
Memory overflow vulnerability leading to unintended control flow and Denial of Service
CVE-2025-6543 is a critical vulnerability (CVSS 9.2) in Citrix Netscaler Gateway, published June 25, 2025. CISA lists it as known to be exploited, since June 30, 2025. EUVD reports exploitation since June 30, 2025. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 10.4%, the 95th percentile. No source names a fixed version.
Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Memory overflow vulnerability leading to unintended control flow and Denial of Service
Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
- Record
CVE-2025-6543- CVSS 4.0
- 9.2 Critical
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L - Weakness
- CWE-119
- Updated
- 2026-11-02
EUVDEUVD-2025-19085
Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
- Record
EUVD-2025-19085- CVSS 4.0
- 9.2 Critical
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-9gqr-6728-fpv3
Memory overflow vulnerability leading to unintended control flow and Denial of Service in...
Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
- Record
GHSA-9gqr-6728-fpv3- CVSS 4.0
- 9.2 Critical
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-119
- Updated
- 2026-11-02
CISA KEV No score
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.
- Record
CVE-2025-6543- Weakness
- CWE-119
- Updated
- 2026-11-02
NVD
Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
- Record
CVE-2025-6543- CVSS 4.0
- 9.2 Critical
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-119
- Updated
- 2026-11-02
Affected products
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | grupooruss/Citrix-cve-2025-6543 | 2025-06-26 |
| PoC in GitHub | lex1010/CVE-2025-6543 | 2025-06-30 |
| PoC in GitHub | abrewer251/CVE-2025-6543_CitrixNetScaler_PoC | 2025-07-03 |
History
| When | Changed | Sources |
|---|---|---|
| 2026-11-03 | exploitation, exploits | |
| 2026-11-02 | created | CVE List, EUVD, GitHub Advisories, CISA KEV, NVD, PoC in GitHub |