VULNpocalypse

CVE-2026-88771: Citrix NetScaler Improper Input Validation Vulnerability

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

Improper input validation vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway. This issue affects ADC: before 14.1-73.37, before 13.1-64.23, before 14.1-73.37 FIPS, and before 13.1.37.279 FIPS and NDcPP; Gateway: before 14.1-73.37 and before 13.1-64.23 leading to an unauthenticated attacker to execute arbitrary commands.

Description quoted from the CVE record (assigned by NetScaler, published 2026-09-27).

Weakness: CWE-20 Improper input validation

How it can be exploited

Exploitable over the network with low attack complexity only when specific conditions are present needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. 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

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.

On CISA KEV since
2026-09-27
US federal deadline
2026-09-30
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-15496, EUVD-2026-87958, GHSA-mx58-p288-86qp

VEDAS cluster: VEDAS:FRIGIDDRIFT

Exploit Observer links 15 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (15)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (12)

Vulnerability databases and vendor advisories (5)

Catalogue entries, not exploit evidence.

News (3)

44 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.822
very likely to be attacked soon
VEDAS
0.979
strong exploit evidence
On CISA KEV
Yes, since 2026-09-27
Detection rule
Nuclei · Suricata
EPSS (chance of attack)
100.1CVE-2026-88771 EPSS over time2026-102026-11-01
VEDAS (exploit evidence)
100.9CVE-2026-88771 VEDAS over time2026-102026-11-01

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.

Who is affected

ProductAffectedNot affected
Citrix NetScaler ADCbefore 14.1-73.37
before 13.1-64.23
before 14.1-73.37 FIPS
before 13.1.37.279 FIPS and NDcPP		Not stated
Citrix NetScaler Gatewaybefore 14.1-73.37
before 13.1-64.23		Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: citrix netscaler_gateway, citrix_systems_inc. netscaler_gateway.

How to fix it

Fixed versions stated in the CVE record: 14.1-73.37, 13.1-64.23, 14.1-73.37 FIPS, 13.1.37.279 FIPS and NDcPP.

CISA 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.

Vendor guidance:

How to detect it

Nuclei template (active check)

Citrix - Improper Input Validation

Improper input validation vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway. This issue affects ADC: before 14.1-73.37, before 13.1-64.23, before 14.1-73.37 FIPS, and before 13.1.37.279 FIPS and NDcPP; Gateway: before 14.1-73.37 and before 13.1-64.23 leading to an unauthenticated attacker to execute arbitrary commands.

Name and description quoted from the template, written by VEDAS.

The template sends 2 requests (GET /logon/LogonPoint/tmindex.html, GET /epa/scripts/linux/nsepa.deb); it decides using dsl matchers. Severity in the template: critical. Marked as verified against a vulnerable target.

Run it against a host you own or are authorised to test:

bash
nuclei -u https://your-host -t CVE-2026-88771.yaml
Show the template (44 lines)
yaml
id: CVE-2026-88771

info:
  name: "Citrix - Improper Input Validation"
  author: vedas-arpsyndicate
  severity: critical
  description: |
    Improper input validation vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway. This issue
    affects ADC: before 14.1-73.37, before 13.1-64.23, before 14.1-73.37 FIPS, and before 13.1.37.279 FIPS and
    NDcPP; Gateway: before 14.1-73.37 and before 13.1-64.23 leading to an unauthenticated attacker to execute
    arbitrary commands.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-88771&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=citrix&match=exact
  classification:
    cvss-metrics: 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
    cvss-score: 9.5
    cve-id: CVE-2026-88771
    cwe-id: CWE-20
  metadata:
    verified: true
    max-request: 2
  tags: cve,cve2026,citrix,netscaler,adc,gateway,rce,preauth,kev

http:
  - raw:
      # 1) sanity check: NetScaler LogonPoint present
      - |
        GET /logon/LogonPoint/tmindex.html HTTP/1.1
        Host: {{Hostname}}

      # 2) passive build fingerprint via the served EPA plugin size
      - |
        GET /epa/scripts/linux/nsepa.deb HTTP/1.1
        Host: {{Hostname}}

    matchers-condition: and
    matchers:
      - type: dsl
        dsl:
          - "status_code_1 == 200"
          - "contains(body_1, 'Citrix') || contains(body_1, 'NetScaler')"
          - "content_length_2 == 11230664"
        condition: and

CVE-2026-88771.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-88771 Citrix - Improper Input Validation. Add them to your Suricata rule set and reload.

Show the rules
suricata
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-88771 Citrix - Improper Input Validation"; flow:established,to_server; http.uri; content:"/logon/LogonPoint/tmindex.html"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2026-88771; reference:url,https://www.exploit.observer/?keyword=CVE-2026-88771&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=citrix&match=exact; sid:1011646; rev:1;)

CVE-2026-88771.rules on GitHub

References

Government sources

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.