NetScaler Gateway

Hackers Exploit Two Critical Citrix NetScaler Zero-Days to Deploy Web Shells and Enable Lateral Movement

Two critical zero-day vulnerabilities in Citrix NetScaler, tracked as CVE-2026-88771 and CVE-2026-88772, are being actively exploited in the wild to achieve unauthenticated remote code execution. Attackers deploy password-protected PHP web shells such as WHIPSHOT and use the Python-based SLAPSHOT tunneling tool for lateral movement inside targeted networks. The flaws affect NetScaler ADC and NetScaler Gateway appliances with default configurations, and one requires DTLS enabled on VPN vServers. Citrix has released patches for versions 13.1-64.23 and 14.1-73.37, while CISA added the issues to its KEV catalog with a September 30, 2026 remediation deadline for U.S. federal agencies. Organizations are advised to hunt for indicators including modified httpd.conf entries, anomalous setuid permissions on /bin/sh, and suspicious files in /var/netscaler/logon/LogonPoint/custom before applying updates.

CISA Sets September 30 Deadline for Federal Agencies to Patch Actively Exploited Citrix NetScaler Zero-Days

CISA has ordered U.S. federal agencies to apply patches by September 30 for two actively exploited zero-day vulnerabilities in Citrix NetScaler ADC and NetScaler Gateway. The flaws, tracked as CVE-2026-88771 and CVE-2026-88772, enable unauthenticated remote code execution under default configurations and affect systems commonly exposed to the internet. CVE-2026-88771 allows remote code execution without authentication on NetScaler ADC and Gateway, while CVE-2026-88772 can trigger remote code execution or denial of service via a memory overflow when DTLS is enabled on VPN vServers. Citrix has released fixes for versions 14.1 and 13.1, including FIPS and NDcPP builds, with minimum required builds of 14.1-73.37 and 13.1-64.23. The advisory also covers six additional vulnerabilities from CVE-2026-88773 to CVE-2026-88778 involving HTTP request smuggling and TCP ISN prediction issues. Unsupported branches NetScaler 12.1 and 13.0 receive no patches, requiring immediate migration. Organizations are advised to inventory instances, check for compromise indicators before patching, and preserve forensic evidence.

Multiple Critical Vulnerabilities Found in Citrix NetScaler ADC and Gateway, Two Actively Exploited

Cloud Software Group disclosed eight vulnerabilities affecting NetScaler ADC and NetScaler Gateway products on September 27, 2026. Two of the issues, CVE-2026-88771 and CVE-2026-88772, have already been confirmed as exploited in the wild, prompting urgent remediation advice. CVE-2026-88771 stems from insufficient input validation and allows unauthenticated remote code execution across all default configurations. CVE-2026-88772 involves a memory overflow that can lead to code execution or denial of service when DTLS is enabled, which occurs by default on VPN vServers. The remaining six vulnerabilities cover code execution, denial of service, and HTTP request smuggling risks, with the advisory rated Critical overall. Organizations are urged to apply patches immediately and investigate potential breaches.

CISA Adds CVE-2026-8452 to KEV Catalog and Orders Federal Agencies to Patch Citrix NetScaler by August 29 2026

CISA has placed CVE-2026-8452 in its Known Exploited Vulnerabilities catalog, compelling US federal agencies to apply patches to Citrix NetScaler before the unusually tight deadline of August 29 2026. The flaw, initially reported as a memory overflow leading to denial of service, has been confirmed through public technical analysis to enable unauthenticated remote code execution with root privileges on unpatched devices. The vulnerability impacts NetScaler ADC and NetScaler Gateway appliances configured as VPN Gateway or AAA virtual servers, with heightened risk in SAML-based deployments acting as either Service Provider or Identity Provider. Attackers have already conducted spray-and-pray campaigns that deploy webshells and perform basic reconnaissance after initial compromise. Tens of thousands of NetScaler instances remain internet-exposed, increasing the likelihood of automated mass exploitation. Citrix has released fixed builds including 14.1-72.61, 13.1-63.18, and 13.1-37.272 or higher for FIPS and NDcPP environments. Organizations are advised to inventory exposed devices, verify versions, hunt for indicators of compromise, and apply additional hardening measures beyond patching.

CISA Orders Federal Agencies to Patch Critical Citrix NetScaler RCE Flaw by August 29 2026

CISA has added CVE-2026-8452 to its Known Exploited Vulnerabilities catalog and set an unusually tight deadline for U.S. federal agencies to remediate the issue in Citrix NetScaler products. The vulnerability, initially described as a denial-of-service condition, is now actively exploited to achieve unauthenticated remote code execution with root privileges on unpatched appliances. Affected configurations include NetScaler ADC and NetScaler Gateway when deployed as VPN Gateway or AAA virtual servers, especially in environments using SAML for single sign-on. Attackers have been observed deploying webshells and performing reconnaissance after initial compromise in a spray-and-pray pattern. Tens of thousands of NetScaler devices remain exposed to the internet, increasing the risk of widespread automated attacks. Citrix has released fixed builds including 14.1-72.61 and 13.1-63.18, along with specific versions for FIPS and NDcPP environments.

Critical Authentication Bypass and Buffer Overflow Flaws Patched in NetScaler ADC and Gateway

Cloud Software Group disclosed two critical vulnerabilities affecting NetScaler ADC and NetScaler Gateway products. CVE-2026-19490 permits authentication bypass via an alternate path when the appliances operate as SSL VPN, ICA proxy, CVPN, or RDP proxy gateways, or when configured as authentication, authorization, and auditing virtual servers. CVE-2026-19489 is a buffer overflow in LSN groups with SIP ALG enabled that can lead to unexpected behavior or denial of service. Both issues received CVSS v4.0 base scores of 9.3 and 8.8 respectively. Fixed builds 14.1-73.32 and 13.1-63.21 are now available along with corresponding FIPS and NDcPP updates.