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Denial of Service in NetScaler ADC and NetScaler Gateway via malformed HTTP/2 requests

IdentifiersCVE-2026-13474CWE-401

CVE-2026-13474 is a high-severity denial-of-service vulnerability in Citrix NetScaler ADC and NetScaler Gateway. The issue is described as a missing release of memory after effective lifetime, resulting in a memory leak condition that can be triggered by malformed HTTP/2 requests. The vulnerability is present when HTTP/2 is enabled in an HTTP Profile that is associated with a NetScaler virtual server of type LB, CS, or VPN, or with a service configured on NetScaler. Repeated malformed HTTP/2 traffic can exhaust resources on the appliance and cause service disruption.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can cause a denial-of-service condition on affected NetScaler ADC or NetScaler Gateway appliances. The impact is on availability: malformed HTTP/2 requests can drive memory consumption through the leak condition until the appliance or affected service becomes unstable, exhibits erroneous behavior, or is unable to continue processing traffic.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, disable HTTP/2 on affected HTTP Profiles or remove the HTTP Profile association from impacted LB, CS, or VPN virtual servers or affected services where operationally feasible. Review HTTP Profile usage across NetScaler deployments to identify exposed configurations. After upgrading, customers not using HTTP Strict Profiles should manually set Http2SmallWndTimeout to 30 seconds using the vendor-supported configuration command.

Remediation

Patch, then assume compromise.

Upgrade affected systems to fixed Citrix builds: NetScaler ADC and NetScaler Gateway 14.1-72.61 or later; NetScaler ADC and NetScaler Gateway 13.1-63.18 or later; NetScaler ADC 14.1-FIPS 14.1-72.61 FIPS or later; NetScaler ADC 13.1-FIPS and 13.1-NDcPP 13.1-37.272 or later. In addition, for CVE-2026-13474, deployments not using HTTP Strict Profiles require a configuration change to fully remediate the issue: set the Http2SmallWndTimeout parameter to 30 seconds. Citrix indicates that where HTTP Strict Profiles are used, the default value is already 30 seconds and the fix is effective immediately after upgrade.
PUBLIC EXPLOITS

Exploits

No valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.

VALID 0 / 1 TOTALView more in app

All candidate exploits were filtered out by Mallory's validation.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Citrix SystemsNetscaler Adcapplication
Citrix SystemsNetscaler Gatewayapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1

Community discussion across Reddit, Mastodon, and other social sources.