CVE-2023-3519
About
Unauthenticated remote code execution
Rainforest analyst review
This is an unauthenticated remote code execution flaw in Citrix NetScaler ADC and Gateway, rooted in a memory-corruption bug reachable when the appliance is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, or RDP Proxy) or as an AAA virtual server. An attacker sends a crafted request to the exposed appliance and executes code on it — no credentials and no user interaction — typically to drop a web shell for persistent access.
NetScaler devices are internet-facing remote-access gateways, the front door to corporate networks, which makes them a premier target. This was exploited as a zero-day in mid-2023 before the patch was available, and thousands of appliances were compromised and back-doored, with web shells surviving on many even after operators applied fixes. Patching is only step one: hunt for web shells and unexpected files on the appliance, and because the device terminates sessions and stores secrets, rotate credentials and keys that lived on any exposed NetScaler rather than assuming the update evicted the intruder.
References
- http://packetstormsecurity.com/files/173997/Citrix-ADC-NetScaler-Remote-Code-Execution.html
- https://support.citrix.com/article/CTX561482/citrix-adc-and-citrix-gateway-security-bulletin-for-cve20233519-cve20233466-cve20233467
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-3519
Related CVEs
Frequently asked questions
What is CVE-2023-3519?
Unauthenticated remote code execution
How severe is CVE-2023-3519?
CVE-2023-3519 carries a CVSS 3.1 base score of 9.8, rated critical. On the Rainforest Risk Index — which weighs the severity alongside how easy the flaw is to reach and how broad its impact is — it scores 99 out of 100, in the critical band.
How is CVE-2023-3519 exploited?
According to the CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H): attack vector Network, attack complexity Low, privileges required None, user interaction None. Impact on confidentiality High, integrity High and availability High.
Which products are affected by CVE-2023-3519?
Public advisories list the following as affected: netscaler application delivery controller, netscaler gateway. Check the references on this page for the exact versions each vendor confirms.
How do I fix CVE-2023-3519?
Apply the fix the vendor published — the references on this page link to the primary advisories and patches. When patching can't happen right away, reduce the exposure of the affected component and watch it for exploitation attempts. Rainforest customers see this vulnerability correlated to their own assets and prioritized by real exposure, not by score alone.
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