NCSC Urges UK organizations to Patch for Citrix NetScaler ADC and Gateway 0-Day Vulnerabilities
The UK NCSC urged immediate patching after two critical Citrix NetScaler zero-days were exploited for unauthenticated remote code execution.
The UK NCSC urged immediate action on eight Citrix NetScaler ADC and Gateway flaws, two of which are already exploited. CVE-2026-88771 and CVE-2026-88772 are rated CVSS 4.0 9.5: the first is unauthenticated remote command execution on default configurations, and the second is a memory overflow that can yield remote code execution or denial of service when DTLS is enabled. Six additional issues, CVE-2026-88773 through CVE-2026-88778, are also fixed. Affected on-premises releases include 14.1 before 14.1-73.37 and 13.1 before 13.1-64.23, and CISA has added the two critical bugs to the Known Exploited Vulnerabilities catalog.
- CVE-2026-88771 allows unauthenticated remote command execution on default NetScaler setups.
- CVE-2026-88772 can cause remote code execution or denial of service with DTLS.
- Both critical flaws are exploited; CISA added them to the KEV catalog.
- Fixed builds include 14.1-73.37 and 13.1-64.23; six further flaws are patched.
- NCSC advises isolating appliances, preserving evidence, patching, then threat hunting.
- CVEs
- CVE-2026-88771CVE-2026-88772CVE-2026-88773CVE-2026-88774CVE-2026-88775CVE-2026-88776CVE-2026-88777CVE-2026-88778CVE-2026-8452
- Vendors
- Citrix
- Products
- NetScaler ADCNetScaler Gateway
- Organizations
- NCSCCISACloud Software Group
- Countries
- United KingdomUnited States
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-8452 | Memory Buffer Overflow in Citrix NetScaler ADC/Gateway Exploited in the Wild | 8.8 | 1% | KEVPoC | KEV |
CVE-2026-88771+1 related CVE | Unauthenticated RCE in Citrix NetScaler ADC and Gateway | 9.5 | 82% | KEVPoC ×5 | KEV |
| CVE-2026-88773 | HTTP request smuggling in Citrix NetScaler ADC and Gateway | 9.3 group max | 3% | PoC ×2 |
From the original article
3 min read at cybersecuritynews.com
The UK National Cyber Security Center (NCSC) has urged organizations to take immediate action against eight vulnerabilities affecting customer-managed Citrix NetScaler ADC and NetScaler Gateway appliances. Two critical flaws, CVE-2026-88771 and CVE-2026-88772, are already being exploited against unmitigated systems, turning routine patching into an urgent incident-response task.
By Guru Baran · cybersecuritynews.com
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