Citrix NetScaler ADC and NetScaler Gateway Memory overflow vulnerability (CVE-2025-6543)

CVE number = CVE-2025-6543

A vulnerability has been discovered in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway (formerly Citrix Gateway) – Memory overflow vulnerability leading to unintended control flow and Denial of Service.

The following supported versions of NetScaler ADC and NetScaler Gateway are affected by the vulnerabilities: 

• NetScaler ADC and NetScaler Gateway 14.1 BEFORE 14.1-47.46
• NetScaler ADC and NetScaler Gateway 13.1 BEFORE 13.1-59.19
• NetScaler ADC 13.1-FIPS and NDcPP  BEFORE 13.1-37.236-FIPS and NDcPP

NetScaler ADC and NetScaler Gateway versions 12.1 and 13.0 are now End Of Life (EOL) and are vulnerable. Customers are recommended to upgrade their appliances to one of the supported versions that address the vulnerabilities. 

Exploits of CVE-2025-6543 on unmitigated appliances have been observed.

Cloud Software Group strongly urges affected customers of NetScaler ADC and NetScaler Gateway to install the relevant updated versions as soon as possible. 

• NetScaler ADC and NetScaler Gateway 14.1-47.46 and later releases
• NetScaler ADC and NetScaler Gateway 13.1-59.19 and later releases of 13.1
• NetScaler ADC 13.1-FIPS and 13.1-NDcPP 13.1-37.236 and later releases of 13.1-FIPS and 13.1-NDcPP. Customers should contact support – https://support.citrix.com/support-home/home to obtain the 13.1-FIPS and 13.1-NDcPP builds that address this issue.

Jason Davies

I am one of the editors here at www.systemtek.co.uk I am a UK based technology professional, with an interest in computer security and telecoms.