Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-88779

Memory overflow vulnerability leading to Denial of Service

NetScaler / ADC · affected before 14.1-73.41

Watch CVE-2026-88779 Browse KEV feed
Severity
CVSS 8.7 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
0.5%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-88779 is an unauthenticated Memory overflow vulnerability leading to Denial of Service affecting NetScaler ADC, Gateway. Vulnerability in NetScaler ADC and NetScaler Gateway. This issue affects ADC: before...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

NetScaler / ADC affected before 14.1-73.41.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Vulnerability in NetScaler ADC and NetScaler Gateway

Vulnerability in NetScaler ADC and NetScaler Gateway.

This issue affects ADC: before 14.1-73.41, before 13.1-64.28, before 14.1-73.41 FIPS, and before 13.1-37.282; Gateway: before 14.1-73.41 and before 13.1-64.28.

NetScaler Affected
ADC
Before 14.1-73.41 Before 13.1-64.28 Before 14.1-73.41 FIPS Before 13.1-37.282
NetScaler Affected
Gateway
Before 14.1-73.41 Before 13.1-64.28
Published
04 Oct 2026
Exploitation Reported
04 Oct 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Citrix

Recorded 04 Oct 2026

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
Citrix First 2026-10-04 07:14 UTC
CISA 2026-10-04 19:40 UTC
The Hacker News 2026-10-05 07:32 UTC
Qualys ThreatPROTECT 2026-10-05 14:20 UTC
TheRegister 2026-10-05 21:20 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

8.7 High

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

0.5%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

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

Recent mention · Citrix

September 2026 Tech Wire

Citrix DaaSNow AvailableDevice PostureWhat’s New: General availability of multiple cloud store support. Gateway serviceWhat’s New: Deprecated ciphers: Three TLS ciphers (TLS1.2-ECDHE-RSA-AES-256-SHA384, TLS1.2-AES256-GCM-SHA384, TLS1-AES-256-CBC-SHA) will be discontinued...

Read full advisory

All CVSS Scores

CVSS v4.0 8.7 High

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

CVSS v3.1 7.5 High

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

All Mentions

Recent mention · Citrix

September 2026 Tech Wire

Citrix · 06 Oct 2026

Citrix DaaSNow AvailableDevice PostureWhat’s New: General availability of multiple cloud store support. Gateway serviceWhat’s New: Deprecated ciphers: Three TLS ciphers (TLS1.2-ECDHE-RSA-AES-256-SHA384, TLS1.2-AES256-GCM-SHA384, TLS1-AES-256-CBC-SHA) will be discontinued after September 2026. Gateway upgrades: Phased approach for reliability; FQDN allowlists (*.nssvc.net) recommended. Workspace Environment Management (WEM) serviceWhat’s New: Self-healing GPOs: "Enforce processing of GPOs" reprocesses GPOs every cycle to correct drift. Privilege elevation: Extends beyond local drives to...

Recent mention · SOCRadar

CVE-2026-88779: Citrix NetScaler Zero-Day

SOCRadar · 06 Oct 2026

CVE-2026-88779: Citrix NetScaler Zero-Day Citrix has patched CVE-2026-88779, a high-severity NetScaler vulnerability that was exploited as a zero-day before fixes became available. The memory overflow affects customer-ma

Recent mention · TheRegister

Security researcher claims they found KVM guest-host escape flaw

TheRegister · 06 Oct 2026

Firecracker MicroVMs, which started at AWS, seem to be the problem

Recent mention · TheRegister

Security researcher claims to they found KVM guest-host escape flaw

TheRegister · 06 Oct 2026

Firecracker MicroVMs, which started at AWS, seem to be the problem

Recent mention · TheRegister

Citrix NetScaler security snafus get even worse amid more 0-day reports

TheRegister · 05 Oct 2026

The new vuln, CVE-2026-88779, is a memory overflow bug that leads to denial of service

Recent mention · The Record

US, Australia warn of latest Citrix vulnerability after NetScaler advisory

The Record · 05 Oct 2026

Citrix confirmed late on Friday that it was “tracking a newly observed issue” related to some customer-managed NetScaler deployments but claimed the problem was not connected to vulnerabilities reported last week that also caused alarm among cybersecurity experts.

Recent mention · Qualys ThreatPROTECT

CISA Warns of Citrix Vulnerability Active Exploitation in Attacks (CVE-2026-88779)

Qualys ThreatPROTECT · 05 Oct 2026

Citrix released an emergency update to address an actively exploited vulnerability impacting Citrix NetScaler ADC and Citrix NetScaler Gateway. Tracked as CVE-2026-88779, successful exploitation of this memory overflow vulnerability may allow an attacker to achieve a denial-of-service condition.  CISA added CVE-2026-88779 to its Known Exploited Vulnerabilities Catalog. CISA urged users to patch the vulnerabilities before … Continue reading "CISA Warns of Citrix Vulnerability Active Exploitation in Attacks (CVE-2026-88779)"

Recent mention · Security Affairs

U.S. CISA adds Citrix NetScaler flaw to its Known Exploited Vulnerabilities catalog

Security Affairs · 05 Oct 2026

U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds Citrix NetScaler flaw to its Known Exploited Vulnerabilities catalog. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added a Citrix NetScaler flaw tracked as CVE-2026-88779 (CVSS score of 8.7), to its Known Exploited Vulnerabilities (KEV) catalog. CVE-2026-88779 is a memory overflow vulnerability in Citrix NetScaler ADC and Gateway […]

Recent mention · The Hacker News

New NetScaler Zero-Day Exploited in Targeted Attacks Can Knock SAML Deployments Offline

The Hacker News · 05 Oct 2026

Ravie LakshmananOct 05, 2026Zero-Day / Vulnerability Citrix has released security updates for a high-severity security flaw in NetScaler ADC and Citrix NetScaler Gateway that has been exploited as part of targeted zero-day attacks. The vulnerability, tracked as CVE-2026-88779, carries a CVSS score of 8.7 out of 10.0. "CVE-2026-88779 is a memory overflow vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway that can lead to denial-of-service under specific deployment conditions," Citrix said. "The issue affects customer-managed NetScaler deployments running affected supported...

Recent mention · Citrix

Understanding and Addressing CVE-2026-88779 in Citrix NetScaler ADC and Citrix NetScaler Gateway

Citrix · 04 Oct 2026

CVE-2026-88779 is a memory overflow vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway that can lead to denial of service under specific deployment conditions. The issue affects customer-managed NetScaler deployments running affected supported versions when the required preconditions are met. Customers should review their deployed versions and configurations, then install the relevant updated versions as soon as possible. Affected Versions The following supported versions are affected when the CVE preconditions (see the section “How to Determine Whether a NetScaler...

Timeline

From disclosure to observed exploitation

  1. 21:20 UTC

    KEV confirmed by TheRegister

    Exploitation attested by an external source

  2. 14:20 UTC

    KEV confirmed by Qualys ThreatPROTECT

    Exploitation attested by an external source

  3. 07:32 UTC

    KEV confirmed by The Hacker News

    Exploitation attested by an external source

  4. 19:40 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  5. 07:14 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  6. 04:20 UTC

    Added to the Previdian watchlist

    Pro and Enterprise Watch users had 15 hours of early warning before CISA KEV. Also 3 hours before Previdian confirmed it as a KEV.

  7. 02:35 UTC

    CVE published

    Vulnerability disclosed publicly

  8. 07:14 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

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Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
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  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-88779

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-88779",
  "confidence": "Confirmed",
  "cvss_score": 8.7,
  "cvss_estimated": false,
  "epss_score": 0.00534,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}