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Vulnerabilities

Vulnerability · CVE-2025-6543

Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability

Published Jun 25, 2025 · catalog updated Jun 17, 2026 · Citrix NetScaler ADC and NetScaler Gateway

Patch now

CVE-2025-6543 is in the CISA known-exploited catalog, due Jul 21, 2025. 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
Critical9.2
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
10.56%
Remediation
Remediation guidance
Affected products
cpe citrix/netscaler application delivery controller · cpe citrix/netscaler gateway · vendor Citrix NetScaler ADC and Gateway · vendor Citrix NetScaler ADC and NetScaler Gateway

Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

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 Gatewayversion unspecified
  • vendor Citrix NetScaler ADC and NetScaler Gatewayversion unspecified

How to fix CVE-2025-6543

What to do

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

Should you patch?

CVE-2025-6543 is in the CISA known-exploited catalog, due Jul 21, 2025. 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, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

What should an analyst verify?

CWE-119: Buffer Overflow. EPSS 10.56%. 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. Jun 25, 2025 · Catalog

    Detected

    Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

  2. Jun 30, 2025 · CISA KEV

    Known exploited

    Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

  3. Jul 21, 2025 · CISA KEV

    Remediation due

    Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

  4. Jun 17, 2026 · Catalog

    Updated

    Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

Sources

  • CISA KEVConfirmed exploitationCVE-2025-6543

    Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2025-6543

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-6543

    30-day exploitation probability 10.6%

    first.org
  • NIST NVDVulnerability recordCVE-2025-6543

    Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2025-6543

    Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.