Cyber Resilience

CVE-2023-3519

RCE in Citrix Netscaler Application Delivery Controller 12.1 – 12.1-55.297

CISA KEVActive ExploitationEUVD ExploitedPublic PoCRansomware-linkedRCE
Published
19 July 2023
Modified
05 August 2026
KEV Added
19 July 2023
Patch / advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.99 100.0th percentile
Risk Priority 97 floored blend · peak EPSS

Summary

CVE-2023-3519 is a critical-severity Code Injection (CWE-94) vulnerability in Citrix Netscaler Application Delivery Controller. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 0.0% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2023-3519 is an unauthenticated remote code execution vulnerability (CWE-94) affecting Citrix ADC and Citrix Gateway appliances. It carries a CVSS 3.1 base score of 9.8, reflecting network attack vector, low attack complexity, and no requirements for authentication or user interaction, with high impact on confidentiality, integrity, and availability.

An unauthenticated attacker with network access can send specially crafted requests that trigger arbitrary code execution on the target appliance, enabling full compromise of the affected system including potential takeover of VPN sessions, authentication flows, or connected infrastructure.

Citrix security bulletin CTX561482 addresses the issue with patches and configuration guidance for supported ADC and Gateway versions; the bulletin is referenced by both vendor and CISA entries. CISA has added the CVE to its Known Exploited Vulnerabilities catalog, confirming observed in-the-wild exploitation.

Public exploit code is available on Packet Storm, and the vulnerability maintains a very high EPSS score (current 0.9348, peak 0.9659), indicating sustained exploitation interest after disclosure.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Unauthenticated remote code execution

CWE(s)
KEV Date Added
19 July 2023

Related Threats

Threat-Actor AttributionAI

UNC4841
Mandiant (Google Cloud) publicly attributed mass exploitation of CVE-2023-3519 in Citrix appliances to UNC4841 espionage operations.

MITRE ATT&CK Enterprise Techniques

T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
T1059.002 AppleScript Execution
Adversaries may abuse AppleScript for execution.
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
T1059.005 Visual Basic Execution
Adversaries may abuse Visual Basic (VB) for execution.
T1059.006 Python Execution
Adversaries may abuse Python commands and scripts for execution.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-6548Same product: Citrix Netscaler Application Delivery Controllerboth on KEV
CVE-2023-4966Same product: Citrix Netscaler Application Delivery Controllerboth on KEV
CVE-2023-6549Same product: Citrix Netscaler Application Delivery Controllerboth on KEV
CVE-2023-4967Same product: Citrix Netscaler Application Delivery Controller
CVE-2023-3466Same product: Citrix Netscaler Application Delivery Controller
CVE-2023-3467Same product: Citrix Netscaler Application Delivery Controller
CVE-2024-5492Same product: Citrix Netscaler Application Delivery Controller
CVE-2024-5491Same product: Citrix Netscaler Application Delivery Controller
CVE-2020-8243Same product class: VPN / SSL gatewayboth on KEV
CVE-2020-8218Same product class: VPN / SSL gatewayboth on KEV

Affected Assets

citrix
netscaler application delivery controller
12.1 — 12.1-55.297 · 12.1 — 12.1-55.297 · 13.0 — 13.0-91.13
citrix
netscaler gateway
13.0 — 13.0-91.13 · 13.1 — 13.1-49.13

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V1.3.1

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-94

Makes persistent code injection into loaded programs impossible when the executable image itself resides on hardware-protected read-only media.

addresses: CWE-94

Dynamically generated code can be produced and executed inside the isolated chamber, preventing host compromise from code-injection payloads.

addresses: CWE-94

Validates inputs used in dynamic code generation to block injected directives.

addresses: CWE-94

Directly prevents execution of attacker-supplied code written into data memory regions.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

PR.PS-06's SDLC practices directly target injection flaws via secure coding and testing (mostly), yet as a single broad outcome it leaves many code-generation specifics unaddressed (partial).

PR.DS-10 none match
prevents

PR.DS-10 protects runtime data confidentiality/integrity but has no bearing on neutralizing externally influenced input during code generation, so neither direction shows any preventive effect.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

Banning unapproved code samples and unauthenticated web services, combined with secure-coding standards and SAST, prevents the dynamic generation or inclusion of attacker-supplied code.

none

Controls that restrict unauthorized or malicious code from being introduced via external networks or removable media limit opportunities for an attacker to inject and execute arbitrary code.

References