CVEvulnerability

CVE-2025-6543

9.2 CRITICAL Known exploited Published 2025-06-25 Modified 2026-06-17 Official page ↗

CISA Known Exploited Vulnerability

Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability — Citrix NetScaler ADC and 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.

Added to KEV: 2025-06-30
Remediation due: 2025-07-21
Ransomware use: Unknown
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Notes: https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX694788 ; https://www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-cve-2025-5777/ ; https://nvd.nist.gov/vuln/detail/CVE-2025-6543

Status: Analyzed
Published: 2025-06-25
Last modified: 2026-06-17
Assigner: [email protected]
CVSS 4.0 ([email protected]): 9.2 CRITICAL — CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1 ([email protected]): 9.8 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses: CWE-119

Description

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

Affected configurations

• citrix netscaler application delivery controller (>= 13.1 < 13.1-37.236) • citrix netscaler application delivery controller (>= 13.1 < 13.1-59.19) • citrix netscaler application delivery controller (>= 14.1 < 14.1-47.46) • citrix netscaler gateway (>= 13.1 < 13.1-59.19) • citrix netscaler gateway (>= 14.1 < 14.1-47.46)

Weakness · CWE (1)

CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer weakness

References