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Vulnerabilities

Vulnerability · CVE-2023-6549

Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

Published Jan 16, 2024 · catalog updated Jun 16, 2026 · Citrix NetScaler ADC and NetScaler Gateway

Patch now

CVE-2023-6549 is in the CISA known-exploited catalog, due Feb 7, 2024. Confirm Citrix NetScaler ADC and NetScaler Gateway against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
High7.5
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
57.63%
Remediation
Remediation guidance
Affected products
cpe citrix/netscaler application delivery controller · cpe citrix/netscaler gateway · vendor Citrix NetScaler ADC and NetScaler Gateway

Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for a denial-of-service when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server. VulnCheck canary evidence.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe citrix/netscaler application delivery controllerversion unspecified
  • cpe citrix/netscaler gatewayversion unspecified
  • vendor Citrix NetScaler ADC and NetScaler Gatewayversion unspecified

How to fix CVE-2023-6549

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2023-6549 is in the CISA known-exploited catalog, due Feb 7, 2024. Confirm Citrix NetScaler ADC and NetScaler Gateway against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

What should an analyst verify?

CWE-119: Buffer Overflow. EPSS 57.63%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jan 17, 2024 · Catalog

    Detected

    Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for a denial-of-service when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

  2. Jan 17, 2024 · CISA KEV

    Known exploited

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

  3. Feb 7, 2024 · CISA KEV

    Remediation due

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

  4. Jun 16, 2026 · Catalog

    Updated

    Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for a denial-of-service when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

Sources

  • CISA KEVConfirmed exploitationCVE-2023-6549

    Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for a denial-of-service when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2023-6549

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2023-6549

    30-day exploitation probability 57.6%

    first.org
  • NIST NVDVulnerability recordCVE-2023-6549

    Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory Read

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2023-6549

    Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for a denial-of-service when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.