Netscaler Application Delivery ControllerApplication · Citrix

CVE-2026-8655

CRITICAL · 9.8 CVSS v3.1 Published 2026-06-30

Fix available

A fix is available. Upgrade to 13.1-37.272 / 13.1-63.18 or later.

See remediation →

100/100

Remediation priority · Urgent

Remotely reachable No privileges Zero-click 8 weeks old

Official description

NVD · unedited

Multiple Memory overflow vulnerabilities in NetScaler ADC and NetScaler Gateway leading to unpredictable or erroneous behavior and Denial of Service if NetScaler ADC is configured as an LB of type Oracle OR NetScaler ADC is configured as a DNS Proxy OR NetScaler ADC is configured as a DNS recursive resolver deployment

In the news

Third-party coverage

covered by 2 outlets this week · latest 1mo ago

Surfaced from public web coverage — external links open in a new tab.

Technical summary

dbcve analysis · moderate confidence

Multiple memory overflow vulnerabilities exist in NetScaler ADC and NetScaler Gateway that can lead to unpredictable behavior or denial of service. These vulnerabilities are triggered specifically when NetScaler ADC is configured as a load balancer of type Oracle, as a DNS proxy, or as a DNS recursive resolver deployment.

MitigationApply vendor-provided patches for CVE-2026-8655 when available. Until patches can be applied, consider disabling or avoiding the affected configurations (Oracle LB, DNS proxy, or DNS recursive resolver) or implement compensating controls such as network segmentation and strict access controls.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

Netscaler Application Delivery ControllerApplication

Affected:< 13.1-37.272>= 13.1, < 13.1-63.18>= 14.1, < 14.1-72.61= 14.1-66.68

Netscaler GatewayApplication

Affected:>= 13.1, < 13.1-63.18>= 14.1, < 14.1-72.61

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

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

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify NetScaler product and version

Run 'show version' or 'nsversion' command in the NetScaler CLI to obtain the installed version number

Affected if Version matches the affected ranges: < 13.1-37.272; >= 13.1 and < 13.1-63.18; >= 14.1 and < 14.1-72.61; or exactly 14.1-66.68 for ADC. For Gateway: >= 13.1 and < 13.1-63.18; >= 14.1 and < 14.1-72.61.
Check for Oracle load balancer configuration

Run 'show lb vserver' or 'show service' commands to list configured load balancers, then inspect each to identify if type is set to ORACLE. Alternatively, run 'stat lb vserver' and look for services with Oracle protocol type.

Affected if Any load balancer virtual server is configured with type ORACLE on an affected NetScaler ADC version.
Check for DNS proxy configuration

Run 'show dns profile' or 'show dns parameter' commands to identify DNS proxy settings. Run 'show service' and look for service type DNS or DNSPROXY. Use 'show dns view' to check DNS view configurations.

Affected if NetScaler ADC is configured as a DNS proxy on an affected version.
Check for DNS recursive resolver configuration

Run 'show dns parameter' and look for 'recursion' or 'recursiveResolver' settings enabled. Check 'show dns profile' for recursive resolver profiles. Verify DNS zone configurations allow recursive queries.

Affected if NetScaler ADC has DNS recursive resolver functionality enabled on an affected version.

The environment is affected if the NetScaler version falls within the vulnerable ranges AND any of these configurations exist: Oracle load balancer, DNS proxy, or DNS recursive resolver.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Upgrade available Upgrade to 13.1-37.272 / 13.1-63.18 / 14.1-72.61 or later

Fixed in 13.1-37.27213.1-63.1814.1-72.61

Interim mitigation

Apply vendor-provided patches for CVE-2026-8655 when available. Until patches can be applied, consider disabling or avoiding the affected configurations (Oracle LB, DNS proxy, or DNS recursive resolver) or implement compensating controls such as network segmentation and strict access controls.

Recommended fix High confidence

Upgrade to NetScaler 13.1-63.18 (for 13.x branches) or 14.1-72.61 (for 14.x branches) or later

1. Identify the current NetScaler ADC or NetScaler Gateway version by running 'show version' or checking the UI dashboard
2. Determine which build branch you are on (13.0, 13.1, or 14.1)
3. For NetScaler ADC on 13.0: Upgrade to 13.1-37.272 or later (13.1-63.18 recommended)
4. For NetScaler ADC on 13.1: Upgrade to 13.1-63.18 or later
5. For NetScaler ADC on 14.1 (excluding 14.1-66.68): Upgrade to 14.1-72.61 or later
6. For NetScaler Gateway on 13.1: Upgrade to 13.1-63.18 or later
7. For NetScaler Gateway on 14.1: Upgrade to 14.1-72.61 or later
8. If currently on 14.1-66.68, upgrade to 14.1-72.61 or later

Caveat Major version upgrades may require configuration changes; test in staging environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Netscaler Application Delivery Controller Scoped from the published advisory

Consultation4.0 h
Implementation8.0 h
Testing6.0 h
Review / QA4.0 h

22.0 hours of engineering $3,860

Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

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References

Primary sources

support.citrix.comVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8655 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2026-8655?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsUpgrade to 13.1-37.272 / 13.1-63.18 or later

Severity 9.8 Critical

Exploit likelihood EPSS, next 30 days 0.6%

Affects: Netscaler Application Delivery Controller

Remediation

A high-priority fix

Fix this in Netscaler Application Delivery Controller 22 hrs · Moderate

Typical engagement from $3,860

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2026-8655 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

In the news

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References