CVE-2026-88771 (GCVE-0-2026-88771)

Vulnerability from cvelistv5 – Published: 2026-09-27 16:02 – Updated: 2026-09-29 03:55
VLAI CISA CIRCL ENISA Shadowserver Previdian
Title
A remote code execution vulnerability exists due to improper input validation, which can allow an unauthenticated attacker to execute arbitrary commands
Summary
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.
Severity
9.5 (Critical)
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
SSVC
Exploitation: active Automatable: yes Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-27 00:00 UTC
CWE
  • CWE-20 - Improper input validation
Assigner
NetScaler CNA under the mitre root
CNA scorecard C 63/100 over 18 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Citrix NetScaler ADC Affected: 0 , < 14.1-73.37 (patch)
Affected: 0 , < 13.1-64.23 (patch)
Affected: 0 , < 14.1-73.37 FIPS (patch)
Affected: 0 , < 13.1.37.279 FIPS and NDcPP (patch)
guessed Create a notification for this product.
Citrix NetScaler Gateway Affected: 0 , < 14.1-73.37 (patch)
Affected: 0 , < 13.1-64.23 (patch)
guessed Create a notification for this product.
Date Public
2026-09-27 15:51
CISA
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 19b155ec-5037-4ef9-8d72-56443e460a6d

Vulnerability ID: CVE-2026-88771

Status: Confirmed

Status Updated: 2026-09-27 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2026-09-27
Asserted: 2026-09-27
Scope
Notes: Citrix NetScaler Improper Input Validation Vulnerability | Affected: Citrix / NetScaler | Description: Citrix NetScaler ADC and NetScaler Gateway contain an improper input validation vulnerability that could allow an unauthenticated attacker to execute arbitrary commands. | 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. | Due date: 2026-09-30 | Known ransomware campaign use (KEV): Unknown | Notes (KEV): Running the provided IOCs in the NetScaler console may help identify indicators of exploitation. Customers must conduct forensic triage as directed by BOD 26‑04 and follow Citrix’s published guidance for mitigations. For more information, please see: https://community.citrix.com/techzone-blogs/110_security-updates/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve-2026-88771-through-cve-2026-88778 ; https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX697096 ; https://support.citrix.com/external/article/CTX694799/steps-to-take-if-netscaler-adc-is-suspec.html ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-88772
Evidence

Type: Vendor Report

Signal: Successful Exploitation

Confidence: 80%

Source: cisa-kev

Details
Cwes CWE-119
Feed CISA Known Exploited Vulnerabilities Catalog
Product NetScaler
Due Date 2026-09-30
Date Added 2026-09-27
Vendorproject Citrix
Vulnerabilityname Citrix NetScaler Improper Input Validation Vulnerability
Knownransomwarecampaignuse Unknown
References
Created: 2026-09-27 22:00 UTC | Updated: 2026-09-27 22:00 UTC
CIRCL
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 7c74e692-5425-4c10-8018-5cd17bb338fa

Vulnerability ID: CVE-2026-88771

Status: Confirmed

Status Updated: 2026-09-28 10:36 UTC

Exploited: Yes

Characteristics
Remote Code Execution: Yes
Authentication Required: No
Local Access Required: Remote
Severity: 100.0
Timestamps
First Seen: 2026-09-28
Asserted: 2026-09-28
Last Seen: 2026-09-28
Created: 2026-09-28 10:54 UTC | Updated: 2026-09-28 10:36 UTC
ENISA
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 41d09cdc-22fd-4ed5-8a47-409484e7f668

Vulnerability ID: CVE-2026-88771

Status: Confirmed

Status Updated: 2026-09-27 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2026-09-27
Asserted: 2026-09-27
Scope
Notes: Affected: Citrix / NetScaler ADC, NetScaler Gateway | Description: A remote code execution vulnerability exists due to improper input validation, which can allow an unauthenticated attacker to execute arbitrary commands | Exploitation type: unknown | CWEs: CWE-20 | Origin source: CNW | Notes: https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX697096
Evidence

Type: Csirt Report

Signal: Successful Exploitation

Confidence: 75%

Source: enisa-cnw-kev

Details
Cwes CWE-20
Euvd EUVD-2026-56431
Notes https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX697096
Catalog ENISA / EU CSIRTs Network (CNW) KEV JSON
Product NetScaler ADC, NetScaler Gateway
Datereported 2026/09/27
Originsource CNW
Patchedsince
Vendorproject Citrix
Exploitationtype unknown
Vulnerabilityname
Threatactorsexploiting
References
Created: 2026-09-28 10:00 UTC | Updated: 2026-09-28 10:00 UTC
Shadowserver
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 4d51aaa2-31bf-4858-ad7e-623dce4b424a

Vulnerability ID: CVE-2026-88771

Status: Confirmed

Status Updated: 2026-10-27 00:00 UTC

Exploited: Yes

Characteristics
Severity: 98.0
Timestamps
First Seen: 2026-09-29
Asserted: 2026-09-29
Last Seen: 2026-10-27
Scope
Asset Exposure: ['internet-facing']
Notes: Affected: Citrix / NetScaler ADC and NetScaler Gateway | Class: app-delivery-controller | Severity: Critical (CVSS 9.8) | IoT: no | In CISA KEV: yes | Honeypot connections on 2026-10-27: 1996
Evidence

Type: Honeypot

Signal: In The Wild Attempts

Confidence: 70%

Source: shadowserver

Details
1D 1
Iot no
Feed Shadowserver Foundation honeypot/exploited-vulnerabilities
Type http-scan
Class app-delivery-controller
7D Avg 0
Vendor Citrix
30D Avg 11
90D Avg 3
Product NetScaler ADC and NetScaler Gateway
Cisa Kev yes
Connections 1996
Observation Date 2026-10-27
Vulnerability Class CVSS
Vulnerability Score 9.8
Vulnerability Severity Critical
References
Created: 2026-10-21 09:13 UTC | Updated: 2026-10-29 01:01 UTC
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: f35abf53-af75-469c-bb1b-006544ecdfe1

Vulnerability ID: CVE-2026-88771

Status: Confirmed

Status Updated: 2026-09-27 16:44 UTC

Exploited: Yes

Timestamps
First Seen: 2026-09-27
Asserted: 2026-09-27
Scope
Notes: A remote code execution vulnerability exists due to improper input validation, which can allow an unauthenticated attacker to execute arbitrary commands | Affected: Citrix NetScaler / ADC, Gateway | CVSS: 9.5 (CRITICAL) | Used in malware: unknown | Listed 5 hours ahead of CISA KEV | Not yet in CISA KEV: False
Evidence

Type: Public Report

Signal: Successful Exploitation

Confidence: 70%

Source: previdian

Details
Feed Previdian (previdian.com)
Title A remote code execution vulnerability exists due to improper input validation, which can allow an unauthenticated attacker to execute arbitrary commands
Cve Id CVE-2026-88771
Vendor Citrix NetScaler
Ghsa Id GHSA-MX58-P288-86QP
Product ADC, Gateway
Added Date 2026-09-27T16:44:00.000Z
Cvss Score 9.5
Epss Score None
Previous Ids
Cvss Severity CRITICAL
Virtual Patch False
Cvss Estimated False
Epss Percentile None
Used In Malware unknown
Vulnerability Id CVE-2026-88771
Ahead Of Cisa Kev 
{
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  "unit": "hour"
}
Not Yet In Cisa Kev False
References
Created: 2026-09-28 17:00 UTC | Updated: 2026-09-28 17:00 UTC
Show details on NVD website
To clipboard 

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}



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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.