CVE-2023-4966

CRITICAL
2023-10-10 [email protected]
9.4
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
Low

Lifecycle Timeline

3
Analysis Generated
Mar 26, 2026 - 11:19 vuln.today
Added to CISA KEV
Oct 24, 2025 - 13:42 cisa
CISA KEV
CVE Published
Oct 10, 2023 - 14:15 nvd
CRITICAL 9.4

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.

Analysis

Citrix NetScaler ADC and Gateway contain an information disclosure vulnerability known as 'CitrixBleed' that leaks sensitive session tokens from memory, enabling authenticated session hijacking at massive scale.

Technical Context

The CWE-119 buffer over-read in NetScaler's HTTP/HTTPS handling leaks data from adjacent memory, including valid session cookies. An unauthenticated attacker can send crafted requests to extract session tokens from the appliance's memory, then replay these tokens to hijack active user sessions.

Affected Products

['NetScaler ADC and Gateway configured as VPN, ICA Proxy, CVPN, RDP Proxy, or AAA virtual server']

Remediation

Apply Citrix patches immediately. Terminate ALL active sessions after patching (session tokens already in attacker hands remain valid). Rotate all credentials. Monitor for unauthorized access using hijacked sessions.

Priority Score

57
Low Medium High Critical
KEV: +50
EPSS: +94.3
CVSS: +47
POC: 0

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CVE-2023-4966 vulnerability details – vuln.today
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