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Response snapshot Oct 26, 2026, 18:57 UTC

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VulnerabilityCVE-2026-88771Known exploitation

Citrix NetScaler Improper Input Validation Vulnerability

Security alert: Multiple vulnerabilities in NetScaler ADC and NetScaler Gateway (CVE-2026-88771, CVE-2026-88772, and others) (updated). Original Japanese title: 注意喚起: NetScaler ADCおよびNetScaler Gatewayにおける複数の脆弱性(CVE-2026-88771、CVE-2026-88772等)に関する注意喚起 (更新)

At a glance

Exploited
Yes: on CISA's Known Exploited list
Severity
9.5 Critical (CVSS 4.0)
Chance of exploitation
82.2% in the next 30 days
CISA federal deadline
Sep 30, 2026: passed
Sources
3 independent sources

What to do

Consult the linked JPCERT/CC advisory for affected versions and the recommended action.

CISA's 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.

Read JPCERT/CC Japan Advisories: Security alert: Multiple vulnerabilities in NetScaler ADC and NetScaler Gateway (CVE-2026-88771, CVE-2026-88772, and others) (updated) (opens a new tab)

CISA federal deadline

Federal due date passed

Applies to covered US federal agencies; it is not your organization's deadline.

Added to the catalog Known ransomware use: Unknown
CISA catalog (opens a new tab)

Scores and how they were measured

CVSS base severity

9.5

Version 4.0As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

82.2%

Scored Percentile 99.7%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    JPCERT/CC Japan Advisories: Security alert: Multiple vulnerabilities in NetScaler ADC and NetScaler Gateway (CVE-2026-88771, CVE-2026-88772, and others) (updated) (opens a new tab)

    Exact official article/advisory identified by the feed; title, source dates, and any supplied article excerpt.

    Published Checked

  2. Primary source

    JPCERT/CC Japan Advisories syndication feed (opens a new tab)

    The RSS/Atom/RDF entry supplied this exact link and any available title, date, and excerpt.

    Published Date not suppliedChecked

  3. Primary source

    CISA KEV entry CVE-2026-88771 (opens a new tab)

    The CVE-2026-88771 catalog entry establishes known exploitation, date added, required action, and the federal due date; not zero-day status.

    Published Checked

  4. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-88771, scored 2026-10-25. This is a model estimate, not proof of exposure.

    Published Checked

  5. Primary source

    CVE Program CNA NetScaler (opens a new tab)

    The published CVE-2026-88771 document's CNA supplies this CVSS 4.0 base score, vector, and authoritative source update date.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 2). Citrix NetScaler Improper Input Validation Vulnerability (CVE-2026-88771). https://kevwire.com/record/CVE-2026-88771

MLA

"Citrix NetScaler Improper Input Validation Vulnerability (CVE-2026-88771)." KEVWire, 2 Oct. 2026, kevwire.com/record/CVE-2026-88771.

Chicago

KEVWire. "Citrix NetScaler Improper Input Validation Vulnerability (CVE-2026-88771)." Last modified October 2, 2026. https://kevwire.com/record/CVE-2026-88771.

Evidence summary (plain text)

Citrix NetScaler Improper Input Validation Vulnerability (Oct 2, 2026).
Security alert: Multiple vulnerabilities in NetScaler ADC and NetScaler Gateway (CVE-2026-88771, CVE-2026-88772, and others) (updated). Original Japanese title: 注意喚起: NetScaler ADCおよびNetScaler Gatewayにおける複数の脆弱性(CVE-2026-88771、CVE-2026-88772等)に関する注意喚起 (更新)
CVSS 9.5 (version 4.0; evidence as of Sep 27, 2026; https://cveawg.mitre.org/api/cve/CVE-2026-88771).
EPSS 82.2% for the following 30 days, scored Oct 25, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-88771&date=2026-10-25).
Sources:
JPCERT/CC Japan Advisories: Security alert: Multiple vulnerabilities in NetScaler ADC and NetScaler Gateway (CVE-2026-88771, CVE-2026-88772, and others) (updated): https://www.jpcert.or.jp/at/2026/at260029.html
JPCERT/CC Japan Advisories syndication feed: https://www.jpcert.or.jp/rss/jpcert.rdf
CISA KEV entry CVE-2026-88771: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-88771&date=2026-10-25
CVE Program CNA NetScaler: https://cveawg.mitre.org/api/cve/CVE-2026-88771
Record ID: CVE-2026-88771.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Documented by a cited source.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
CISA federal due date: Sep 30, 2026. This is a deadline for covered US federal agencies, not the reader's SLA.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 14:11 UTC. Ingestion is not an independent editorial investigation.

The English title is KEVWire's pattern-and-glossary translation of the JPCERT/CC Japanese title, not an official JPCERT/CC translation. The feed supplies only a title, date, and any short excerpt; consult the linked advisory for affected versions and details.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

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