CVE-2025-6543

Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability

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

CVSS 9.8 KEVNo patch available

This record: live connection— last retrieved: 24 September 2026 at 05:10.

Vendor

Citrix

Product

NetScaler ADC and Gateway

up to version cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:fips:*:*:*

Published

25 June 2025

Last modified

17 June 2026

Original source information

Taken directly from NVD, CISA or the vendor — sometimes in English, unchanged from the source.

Technical description

CVSS 3.1 — vector details

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack vector

NETWORK

Privileges required

NONE

User interaction

NONE

Confidentiality

High

Integrity

High

Availability

High

EPSS — Exploit Prediction Scoring System

Probability of exploitation within 30 days

10.1%

Percentile

95e

Source: FIRST.org, updated on 23 September 2026.

Patch information

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

IACS Radar assessment

Our own interpretation and context for the source data above.

IACS Radar assessment

Our own interpretation and context for this vulnerability — not an official source.

IACS Radar priority score

87/ 100

Based on CVSS 9.8, EPSS 10.1%, industrial relevance 55/100; raised due to confirmed active exploitation (KEV) and relevance to internet exposure.

Combines CVSS, EPSS, KEV status, industrial relevance and exposure relevance — a complement to, not a replacement for, the individual scores below and above.

Conditions for exploitation

•Network access to the affected device or segment is required.
•No valid credentials are needed.
•No user interaction required.

Operational impact & energy relevance

Possible loss of visibility of or control over the process upon successful exploitation.

Assessed as relevant to the energy sector based on: Productbeschrijving komt overeen met de categorie "protocol-gateway", een typisch OT/ICS-componenttype. Description mentions industrial protocol: rdp. Included in the CISA KEV catalogue: confirmed evidence of actual exploitation.

This product uses protocols that are relevant to internet exposure analysis. An internet-reachable service is not automatically vulnerable.

Recommended defensive measures

•Apply the latest firmware or software update and validate its integrity.
•Restrict network access to the affected device to a dedicated OT management segment.
•Implement network segmentation in line with zones and conduits (IEC 62443-3-2).
•Monitor for abnormal protocol traffic using an OT-aware detection system.

Industrial relevance score

55/ 100

• Product description matches the category "protocol-gateway", a typical OT/ICS component type.
• Description mentions industrial protocol: rdp.
• Included in the CISA KEV catalogue: confirmed evidence of actual exploitation.

Classification is provisional; manual verification by an OT security analyst is recommended.

Classified by IACS Radar-analysepijplijn (geautomatiseerd) on 24 September 2026.

IEC 62443 mapping

IEC 62443-4-1FR3 · Systeemintegriteit

Automatic IACS Radar assessment based on the reported CWE weakness classification; not an official certification statement.

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