Home/CVE/Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
CVE

CVE-2023-4966

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.

CRITICAL · CVSS 9.4 ⚠ CISA KEV EPSS 0.94348 Ransomware: known
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • Linked to known ransomware campaigns
  • SSVC exploitation status: active
  • EPSS ≥ 0.50 - high probability of exploitation in the next 30 days
  • EPSS percentile: top 0% of all CVEs by exploitation likelihood
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules10 YARA rules4
⬢

Required Remediation

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.

◆

Threat Actors Linked

11
actorALPHV / BlackCat
actorBlack Basta
actorCuba
actorLockBit Operators
actorMedusa
actorQilin
⬡

Weakness Classification

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
▤

Affected Products & Versions

8
citrix netscaler application delivery controller>= 12.1 and < 12.1-55.300
citrix netscaler application delivery controller>= 13.0 and < 13.0-92.19
citrix netscaler application delivery controller>= 13.1 and < 13.1-37.164
citrix netscaler application delivery controller>= 13.1 and < 13.1-49.15
citrix netscaler application delivery controller>= 14.1 and < 14.1-8.50
citrix netscaler gateway>= 13.0 and < 13.0-92.19
citrix netscaler gateway>= 13.1 and < 13.1-49.15
citrix netscaler gateway>= 14.1 and < 14.1-8.50
⚠

Public Exploits & PoCs

2
nucleiCitrix Bleed - Leaking Session Tokenshigh
pocpacketstormsecurity.com · Citrix-Bleed-Session-Token-Leakage-Proof-Of-Concept.htmlpacketstormsecurity.com
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Detection Rules (IDS/IPS)

3
et-openET EXPLOIT Citrix ADC and NetScaler Gateway Information Disclosure Attempt (CVE-2023-4966)attempted-admin
et-openET EXPLOIT Citrix ADC and NetScaler Gateway Information Disclosure - Successful Response (CVE-2023-4966)successful-admin
et-openET EXPLOIT Citrix ADC and NetScaler Gateway Information Disclosure Attempt (CVE-2023-4966)attempted-admin
Open rulesets (ET Open, Snort Community, abuse.ch) link to source. Commercial rulesets are reference-only.
◈

Sigma Hunt Rules

10
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
relatedcriticalAntivirus Password Dumper Detection
relatedcriticalHacktool Execution - Imphash
relatedcriticalHackTool - Rubeus Execution
relatedcriticalPotential Credential Dumping Via LSASS Process Clone
relatedcriticalWCE wceaux.dll Access
relatedcriticalHackTool - Dumpert Process Dumper Default File
▣

Scoring & Timeline

9.4
CRITICAL · CVSS v3.1 · secure@citrix.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD10 Oct 2023 · 02:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
yes
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

2
cisaKEV-CVE-2023-4966
splunk-security-contentb593cac5-dd20-4358-972a-d945fefdaf17
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://support.citrix.com/article/CTX579459Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-4966US Government Resource
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