Gateway
CVE-2021-22955
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource consumption limits
MITRE ATT&CK
1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. |
| Exploit ScenarioDerived | A remote attacker could cause denial of service by exhausting system resources by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAI
A unauthenticated denial of service vulnerability exists in Citrix ADC <13.0-83.27, <12.1-63.22 and 11.1-65.23 when configured as a VPN (Gateway) or AAA virtual server could allow an attacker to. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Implement rate limiting, set resource quotas, validate input sizes, use timeouts.
Affects your stack
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Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Uncontrolled Resource Consumption (CWE-400), which allows attackers to cause denial of service by exhausting system resources. A unauthenticated denial of service vulnerability exists in Citrix ADC <13.0-83.27, <12.1-63.22 and 11.1-65.23 when configured as a VPN (Gateway) or AAA virtual server could allow an attacker to cause a temporary disruption of the Management GUI, Nitro API, and RPC communication. Affected products include: Citrix Application Delivery Controller Firmware, Citrix Gateway.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
A unauthenticated denial of service vulnerability exists in Citrix ADC <13.0-83.27, <12.1-63.22 and 11.1-65.23 when configured as a VPN (Gateway) or AAA virtual server could allow an attacker to cause a temporary disruption of the Management GUI, Nitro API, and RPC communication.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)NVD
Citrix NetScaler ADC and NetScaler Gateway deployments running builds prior to 14.1-73.37 or 13.1-64.23 (including the c
Unauthenticated command execution in Citrix NetScaler ADC (before 14.1-73.37, before 13.1-64.23, and the corresponding F
A remote, unauthenticated attacker can cause a denial-of-service condition on NetScaler ADC and NetScaler Gateway applia
An insufficient input validation vulnerability exists in Citrix NetScaler ADC and NetScaler Gateway when configured as a
The Gzip file parser in AVG Anti-Virus 10.0.0.1190, Bitdefender 7.2, Command Antivirus 5.2.11.5, Emsisoft Anti-Malware 5
The TAR file parser in AhnLab V3 Internet Security 2011.01.18.00, Avira AntiVir 7.11.1.163, Antiy Labs AVL SDK 2.0.3.7,
The CAB file parser in Dr.Web 5.0.2.03300, Trend Micro HouseCall 9.120.0.1004, Kaspersky Anti-Virus 7.0.0.125, Sophos An
HTTP request smuggling (CWE-444) in Citrix NetScaler ADC and NetScaler Gateway allows unauthenticated, remote attackers
Predictable value generation in Citrix NetScaler ADC and Gateway (CWE-342) lets unauthenticated remote attackers predict
The TAR file parser in Avira AntiVir 7.11.1.163, Antiy Labs AVL SDK 2.0.3.7, Quick Heal (aka Cat QuickHeal) 11.00, Emsis
Remote unauthenticated attackers can trigger a memory overflow in Citrix NetScaler ADC and Gateway, leading to unpredict
A memory overflow in Citrix NetScaler ADC and NetScaler Gateway can be triggered by unauthenticated remote attackers (CV
GitHub PoC
Exploit-DB