CVE-2026-19489Network attack vector

Service interrupt via SIP ALG overflow

Published Aug 19, 2026 · Updated Aug 20, 2026

Memory overflow in Citrix NetScaler ADC and NetScaler Gateway before 14.1-73.32 and 13.1-63.21 allows remote attackers to interrupt service. Citrix describes the flaw only as a memory overflow, but states that it is reachable when SIP ALG is enabled on a Large Scale NAT group configuration, indicating unsafe handling of SIP traffic in that processing path; no function-level details are public. Exposure requires an LSN deployment with SIP ALG enabled, and the published impact is bounded to unpredictable behavior or denial of service rather than confirmed code execution.

CVSS severity8.8
High
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory overflow in Citrix NetScaler ADC and NetScaler Gateway before 14.1-73.32 and 13.1-63.21 allows remote attackers to interrupt service. Citrix describes the flaw only as a memory overflow, but states that it is reachable when SIP ALG is enabled on a Large Scale NAT group configuration, indicating unsafe handling of SIP traffic in that processing path; no function-level details are public. Exposure requires an LSN deployment with SIP ALG enabled, and the published impact is bounded to unpredictable behavior or denial of service rather than confirmed code execution.

The record

CVE
CVE-2026-19489
Published
Aug 19, 2026
Updated
Aug 20, 2026
Vendor
Cloud Software Group
Product
NetScaler Gateway
Classifications
CWE-119, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=13.1 <=63.21
  2. Affected versionversion=14.1 <=73.32

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cloud Software Group · NetScaler Gatewayversion=13.1 <=63.21; version=14.1 <=73.32
Cloud Software Group · NetScaler ADCversion=13.1 <=63.21; version=14.1 <=73.32

Published CVSS scores

8.8NetScalerCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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