CVE-2023-3519 — Citrix Netscaler Application Delivery Controller
CISA KEVRansomwareAs of 2025-10-24, CVE-2023-3519 is a CRITICAL-severity vulnerability in Citrix Netscaler Application Delivery Controller, CVSS v3.1 9.8, EPSS 93.8% (99.8th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-07-19), with a US federal remediation deadline of 2023-08-09, and CISA links it to known ransomware campaigns. Threadlinqs Intelligence links 3 tracked threat campaigns to CVE-2023-3519, most recently “2026 Ransomware Surge Targeting US Organizations: Identity-First Compromise, BYOVD, and Living-Off-the-Cloud Exfiltration (Qilin, Akira, Clop, INC Ransom, Play, DragonForce, Sinobi)”.
Last updated: 2025-10-24
What is CVE-2023-3519?
Unauthenticated remote code execution
The record classifies CVE-2023-3519 under weakness class CWE-94. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 4 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 1152 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9.8 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS (FIRST)
- 93.8% probability of exploitation in the next 30 days, higher than 99.8% of all scored CVEs
- CISA KEV
- Listed since 2023-07-19, federal remediation deadline 2023-08-09 — used in known ransomware campaigns
- Threadlinqs priority
- 10/10 — CISA lists it as used in ransomware, which Threadlinqs scores at the maximum
- Published
- 2023-07-19, last modified 2025-10-24
Is CVE-2023-3519 being exploited?
CISA added CVE-2023-3519 to the Known Exploited Vulnerabilities catalog on 2023-07-19, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2023-08-09 under BOD 22-01. CISA flags the vulnerability as one used in known ransomware campaigns. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.
Affected products and versions
- Citrix: Netscaler Application Delivery Controller, Netscaler Gateway
Showing 2 of 4 recorded product entries.
How to fix CVE-2023-3519
The record marks a vendor fix as available for CVE-2023-3519. Patch reference: https://support.citrix.com/article/CTX561482. Vendor advisory: https://support.citrix.com/article/CTX561482/citrix-adc-and-citrix-gateway-security-bulletin-for-cve20233519-cve20233466-cve20233467. Because CVE-2023-3519 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2023-08-09. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2023-3519
3 tracked threats in the Threadlinqs corpus reference CVE-2023-3519, either in the campaign’s CVE list or as an indicator on the campaign record.
- 2026 Ransomware Surge Targeting US Organizations: Identity-First Compromise, BYOVD, and Living-Off-the-Cloud Exfiltration (Qilin, Akira, Clop, INC Ransom, Play, DragonForce, Sinobi) — HIGH · 2026-08-23
- FortiBleed Credential-Harvesting Campaign Against 430,000 FortiGate Firewalls Feeds INC Ransom and Lynx Ransomware Operations — CRITICAL · 2026-07-02
- INC Ransom Affiliate Network Targeting Pacific Critical Infrastructure (AU/NZ/Tonga Joint Advisory) — CRITICAL · 2026-03-09
Sources
Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.
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