# CVE-2025-6543: Citrix NetScaler ADC and Gateway buffer overflow

Source: https://junglewise.ai/threats/cve-2025-6543-citrix-netscaler-adc-and-gateway-buffer-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-06-30. Updated: 2026-05-15  
License: CC BY 4.0 with a link back

CVE-2025-6543 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2025-06-30

Citrix NetScaler ADC and Gateway, which are used to provide secure remote access and load balancing for corporate applications, are affected by a critical security flaw. An attacker can exploit this vulnerability to disrupt services or potentially gain unauthorized control over the device. This issue is particularly serious as it is known to be actively exploited in the wild, potentially allowing attackers to bypass security controls or crash the gateway.

Technologies: [Citrix Gateway](https://junglewise.ai/threats/technologies/gateway), [Citrix NetScaler ADC](https://junglewise.ai/threats/technologies/netscaler-adc). Vendors: [Citrix](https://junglewise.ai/threats/vendors/citrix).

## Quick answers

**Is CVE-2025-6543 exploited in the wild?** Yes. CVE-2025-6543 is known to be exploited in the wild, first recorded on 30 June 2025. Treat it as urgent.

**How severe is CVE-2025-6543?** Critical severity, with a CVSS score of 9.8, published 30 June 2025.

**Which products and versions are affected?** Citrix NetScaler ADC 13.1 before 13.1-59.19, 13.1 FIPS before 13.1-37.236, 14.1 before 14.1-47.46; Citrix NetScaler Gateway 13.1 before 13.1-59.19, 14.1 before 14.1-47.46.

**Is there a fix for CVE-2025-6543?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2025-6543 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2025-6543?** Check whether you run Citrix Gateway, Citrix NetScaler ADC or Citrix NetScaler Gateway at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A memory buffer overflow vulnerability (CWE-119) exists in Citrix NetScaler ADC and Gateway. The flaw is triggered when the device is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, or RDP Proxy) or as an AAA virtual server. A remote, unauthenticated attacker can exploit this over the network to cause a denial-of-service (DoS) condition or achieve unintended control flow, potentially leading to remote code execution. The vulnerability has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation. Patches are available in versions 13.1-59.19, 14.1-47.46, and related maintenance releases.

## Affected products

- Citrix NetScaler ADC 13.1 before 13.1-59.19, 13.1 FIPS before 13.1-37.236, 14.1 before 14.1-47.46
- Citrix NetScaler Gateway 13.1 before 13.1-59.19, 14.1 before 14.1-47.46

## Timeline

- 2025-06-25: disclosed: Initial disclosure by Citrix
- 2025-06-30: kev added: Added to CISA Known Exploited Vulnerabilities catalog
- 2025-06-30: advisory: NVD publication date

## Related threats

- [Citrix NetScaler ADC memory overflow in LDAP authentication](https://junglewise.ai/threats/cve-2026-111342-memory-overflow-in-ldap-authentication-can-lead-to-unpredictable)
- [Citrix NetScaler memory overflow in client-certificate authentication](https://junglewise.ai/threats/cve-2026-111341-memory-overflow-in-client-certificate-authentication-can-lead-to)
- [Citrix NetScaler memory overflow in KBA authentication](https://junglewise.ai/threats/cve-2026-111340-memory-overflow-in-kba-knowledge-based-authentication-can-lead)
- [Citrix NetScaler ADC memory overflow in Email OTP authentication](https://junglewise.ai/threats/cve-2026-107415-memory-overflow-in-email-otp-authentication-can-lead-to)
- [Citrix NetScaler ADC memory overflow in WebAuth authentication](https://junglewise.ai/threats/cve-2026-107414-memory-overflow-in-webauth-authentication-can-lead-to)