Citrix Bleed (CVE-2023-4966)
Unauthenticated sensitive information disclosure
Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
Required action
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 notes
https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/, https://support.citrix.com/article/CTX579459/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20234966-and-cve20234967 ; https://nvd.nist.gov/vuln/detail/CVE-2023-4966
Also Known as Citrix Bleed
Citrix Bleed is a memory disclosure flaw in NetScaler ADC and NetScaler Gateway that exposes session tokens, allowing session hijacking; Citrix published its bulletin on October 10, 2023. Tenable credits Assetnote researchers with the name, and CISA documented LockBit 3.0 affiliates exploiting it.
Other names: CitrixBleed
Name sources
Description
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.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:LExploitation Context
as of October 14, 2026- CISA added CVE-2023-4966 to the KEV catalog 8 days after its CVE record was published. The median for entries added in 2023 is 12 days.
- It is one of 27 Citrix entries in the CISA KEV catalog, and one of 3 added in 2023.
- Its current EPSS score (100.0%) is higher than that of 97% of CISA KEV entries.
Affected Products
| Vendor | Product | Affected versions |
|---|---|---|
| Citrix | Citrix NetScaler ADC | 14.1 to <8.50 13.1 to <49.15 13.0 to <92.19 13.1-FIPS to <37.164 12.1-FIPS to <55.300 12.1-NDcPP to <55.300 |
| Citrix | Citrix NetScaler Gateway | 14.1 to <8.50 13.1 to <49.15 13.0 to <92.19 |
References
2 LinksRecord Details
More from Citrix
Citrix NetScaler ADC and NetScaler Gateway Code Injection Vulnerability
Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
Citrix NetScaler ADC and NetScaler Gateway Code Injection Vulnerability
Memory overflow vulnerability leading to unpredictable or erroneous behavior and Denial of Service
Related
Tool categories
CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.