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Fencer Vulns
critical 9.8

CVE-2023-3519 kev+ ransomware in the critical feed json

Unauthenticated remote code execution

published 2023-07-19 3 y ago modified 2026-08-05 3 mo ago also EUVD-2023-44176

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2023-07-19, used in ransomware
epss
99.7%
EPSS 99.7% chance of exploitation in 30 days, percentile 99.9%
public exploits
1
Metasploit, plus a Nuclei check

Summary

Unauthenticated remote code execution

Patch / fix

cisa required action Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

  • Citrix NetScaler ADC 37.159, 49.13, 55.297, 91.13
  • Citrix NetScaler Gateway 49.13, 91.13

Timeline

  1. First public exploit (Metasploit exploit/freebsd/http/citrix_formssso_target_rce)
  2. CISA SSVC: exploitation active
  3. Added to CISA KEV
  4. Published
  5. CISA patch deadline

Known exploited

Added
3 y ago
Patch by
2023-08-09 (3 y ago)
Ransomware
Known to be used in ransomware campaigns
Required action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Vendor, product
Citrix, NetScaler ADC and NetScaler Gateway
CISA name
Citrix NetScaler ADC and NetScaler Gateway Code Injection Vulnerability

Ransomware

Groups reported to have exploited it in intrusions.

  • Pioneer Kitten suspected state-sponsored
  • RansomHub ransomware gang

reported by cisa.govcisa.gov

Ransomware Vulnerability Matrix by BushidoUK (github.com/BushidoUK/Ransomware-Vulnerability-Matrix), reformatted per CVE. CC BY 4.0

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1190 Exploit Public-Facing Application exploitation
  • T1574 Hijack Execution Flow exploitation
  • T1105 Ingress Tool Transfer primary impact
  • T1087.002 Domain Account secondary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
no
Technical impact
total
Assessed
3 y ago

Exploit prediction

99.75% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Citrix NetScaler ADC
  • Citrix NetScaler Gateway

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.