CVE-2026-8452: Citrix NetScaler ADC and NetScaler Gateway Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Citrix NetScaler ADC and NetScaler Gateway. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-08-26, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-08-29; treat that as the outer limit, not the target.
• EPSS 1.0%, percentile 63: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 63% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Editorial verdict: Act now. NetScaler CVE-2026-8452: DoS Bug Exploited as Pre-Auth RCE — Any NetScaler configured as a Gateway or AAA server that is still below the June 30 builds needs patching today and a check for web shells; the bug the vendor called DoS is a public pre-auth RCE under attack.

What it is

Memory overflow vulnerability NetScaler ADC and NetScaler Gateway leading to unpredictable or erroneous behavior and Denial of Service if the appliance is configured as a Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server

CISA’s summary

Citrix NetScaler ADC and NetScaler Gateway contain an improper restriction of operations within the bounds of a memory buffer vulnerability which could lead to denial of service.

Weakness type: CWE-119.

Product: Citrix NetScaler ADC and NetScaler Gateway · Assigned by: NetScaler · Published: 2026-06-30

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-08-26; federal due date 2026-08-29. Known ransomware use: Unknown.
• CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
• CISA SSVC assessment: exploitation active, automatable yes, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 1.01% probability of exploitation activity in the next 30 days; percentile 63.

Timeline

• 2026-06-30 — CVE record published by NetScaler
• 2026-06-30 — erroneo.us brief: NetScaler CVE-2026-8452: DoS Bug Exploited as Pre-Auth RCE
• 2026-08-26 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-08-27 — CVE record last updated
• 2026-08-29 — CISA remediation deadline for US federal agencies

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Listed in CISA KEV notes (support.citrix.com) support.citrix.com

Vulnerability records

1. CVE.org record CVE-2026-8452 cve.org
2. NVD entry CVE-2026-8452 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov
2. Listed in CISA KEV notes (cisa.gov) cisa.gov
3. Listed in CISA KEV notes (cisa.gov) cisa.gov

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