Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
Sensitive information disclosure in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.
What happened
Sensitive information disclosure in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.
CISA lists it as exploited, added 18 Oct 2023.
Does it affect you
Names Citrix NetScaler ADC. Enter the product and version you run to place it against the affected range the vendor published.
What to do
- Follow the vendor advisory for the fixed release and any interim mitigation.
support.citrix.com - Apply mitigations and kill all active and persistent sessions per vendor instructions [https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/] OR discontinue use of the product if mitigations are unavailable.
cisa.gov
CISA’s notes for this entry:
Affected, as published to NVD
- citrix-adc
- Citrix NetScaler ADC: 12.1 up to the fix in 12.1-55.300
The record
- NVD status
- Analyzed
- Published
- 10 Oct 2023, last modified 31 Jul 2026 (NVD)
- Severity
- CVSS 3.1 base score 7.5, High — computed here from the vector; NVD states 7.5.
- Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weakness
- CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer (NVD; names by MITRE)
- Exploitation
- Listed in CISA’s Known Exploited Vulnerabilities catalogue since 18 Oct 2023; federal remediation due 08 Nov 2023. CISA records known use in ransomware campaigns. CISA entry
- Exploit probability
- EPSS 100.0%, 100th percentile — FIRST, scored 23 Oct 2026. FIRST EPSS
- Vendor
- Citrix · NetScaler ADC and NetScaler Gateway (CISA)
References on the NVD record
- support.citrix.com/article/CTX579459Vendor Advisory
- packetstormsecurity.com/files/175323/Citrix-Bleed-Session-Token-Leakage-Proof-Of-Concept.htmlThird Party AdvisoryVDB Entry
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-4966US Government Resource
Sources
The verdict above is computed from the products and versions you entered and the affected ranges the vendor published to NVD. It does not inspect your environment, and this site never reports a product as unaffected: why.