CVE-2021-22956Network attack vector

Management service disruption via resource exhaustion

Published Dec 7, 2021 · Updated Aug 3, 2024

Uncontrolled resource consumption in Citrix ADC, Gateway, and SD-WAN WANOP allows attackers to disrupt management services. Citrix has not disclosed the resource-consuming request or code path affecting the Management GUI, Nitro API, and RPC communication. Reachability requires NSIP or SNIP access to a management interface; disruption is temporary, and CLI access remains available.

CVSS severity7.5
High
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Citrix ADC, Gateway, and SD-WAN WANOP allows attackers to disrupt management services. Citrix has not disclosed the resource-consuming request or code path affecting the Management GUI, Nitro API, and RPC communication. Reachability requires NSIP or SNIP access to a management interface; disruption is temporary, and CLI access remains available.

The record

CVE
CVE-2021-22956
Published
Dec 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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