Trending
CVE-2021-22955

CVE detail

CVE-2021-22955

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.

CVSS 7.5 · HighBuzz score 17.5

Buzz score

Why this CVE is surfacing

Buzz score total 17.5

This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.

Buzz score components · mention 11.0 · diversity 6.5 · KEV 0.0 · OTX 0.0 · PoC 0.0

Mention score

11.0

2 evidence mentions in the snapshot

Diversity score

6.5

2 sources across 1 categories

KEV score

0.0

No KEV entry observed

OTX score

0.0

0 OTX pulses

PoC score

0.0

0 repos · best confidence N/A

Best PoC traction

Maximum stars on a matched PoC repo

Why it matters now

Mention timeline

Total mentions: 0; within the 30d window
Peak daily: 0; highest bucket

Evidence

Source links by recency

Newest mentions first

2 source links · newest first

Citrix addresses a critical flaw in ADC, GatewaySecurity Affairs
Citrix addressed two vulnerabilities affecting Citrix ADC, Gateway, and SD-WAN, one of them is a critical issue leading to DoS. Citrix has released security updates to address two vulnerabilities in ADC, Gateway, and SD-WAN, including a critical flaw, tracked as CVE-2021-22955, that can be exploited to trigger a denial of service (DoS) condition. The CVE-2021-22955 […]
newssecurityaffairs.comNov 10, 2021, 3:42 PM
Citrix Patches Critical Vulnerability in ADC, GatewaySecurityWeek
Citrix this week released patches for a couple of vulnerabilities affecting Citrix ADC, Gateway, and SD-WAN, including a critical bug leading to denial of service (DoS).
newswww.securityweek.comNov 10, 2021, 2:48 PM

Exploit code

Public exploit repository references

Public PoC repositories are third-party, potentially unsafe artifacts. Treat their code as untrusted and use it only on authorized systems in an isolated, least-privilege environment. cvebuzz does not execute the code or verify that an exploit works.

0 repository references · best confidence N/A · max 0 stars

No public PoC repositories have been matched yet.

Related records

Similar CVEs

6 related CVEs with shared weakness or product evidence

CVE-2021-22956
An uncontrolled resource consumption vulnerability exists in Citrix ADC <13.0-83.27, <12.1-63.22 and 11.1-65.23 that could allow an attacker with access to NSIP or SNIP with manag…
CVSS 7.5 · High
2 mentions
CVE-2020-8299
Citrix ADC and Citrix/NetScaler Gateway 13.0 before 13.0-76.29, 12.1-61.18, 11.1-65.20, Citrix ADC 12.1-FIPS before 12.1-55.238, and Citrix SD-WAN WANOP Edition before 11.4.0, 11.…
CVSS 6.5 · Medium
CVE-2020-8246
Citrix ADC and Citrix Gateway 13.0 before 13.0-64.35, Citrix ADC and NetScaler Gateway 12.1 before 12.1-58.15, Citrix ADC 12.1-FIPS before 12.1-55.187, Citrix ADC and NetScaler Ga…
CVSS 7.5 · High
CVE-2022-27508
Unauthenticated denial of service
CVSS 7.5 · High
CVE-2022-27507
Authenticated denial of service
CVSS 6.5 · Medium
CVE-2019-18177
In certain Citrix products, information disclosure can be achieved by an authenticated VPN user when there is a configured SSL VPN endpoint. This affects Citrix ADC and Citrix Gat…
CVSS 6.5 · Medium

External lookup

Potential internet exposure

Potential exposure only — not proof of vulnerability.Shodan results indicate potentially internet-exposed products, not confirmed vulnerable systems. They do not confirm that any returned system is vulnerable to CVE-2021-22955.

Product-level CPE searches intentionally omit version fields and NVD version-range or configuration certainty. Verify the exact product version and configuration independently.

Sign-in required. Shodan requires you to sign in to run these filter searches.

Product CPE queries

Derived from this CVE's existing NVD CPE 2.3 records; the application, operating-system, or hardware part is retained.

cpe:2.3:h:citrix:application_delivery_controllerSearch this product on Shodan
cpe:2.3:o:citrix:application_delivery_controller_firmwareSearch this product on Shodan
cpe:2.3:a:citrix:gatewaySearch this product on Shodan

Exact CVE query

Eligible paid Shodan plan required

Shodan's exact vuln: filter is separate from the product searches above and requires an eligible paid Shodan plan.

vuln:CVE-2021-22955Search this CVE on Shodan

These are outbound search links only. cvebuzz makes no Shodan API call, uses no Shodan API key, and does not display live result counts.

Metadata

Canonical fields

NVD status

Unavailable

Published

Dec 7, 2021

Modified

Jun 17, 2026

Official record

Authoritative NVD record

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE IDs

Vendor classifications

How this vector reads

CVSS 3.1 base metrics decoded below. This explanation does not recalculate or change the NVD score.

Attack Vector (AV): Network. The vulnerable system can be reached across network boundaries.
Attack Complexity (AC): Low. No special conditions beyond the attacker-controlled steps are required.
Privileges Required (PR): None. The attacker needs no privileges on the vulnerable system.
User Interaction (UI): None. Exploitation does not require another user to act.
Scope (S): Unchanged. Impacts remain within the vulnerable security authority.
Confidentiality Impact (C): None. There is no direct impact to this security property.
Integrity Impact (I): None. There is no direct impact to this security property.
Availability Impact (A): High. There is a total or serious impact to this security property.

Signals

Exploitation indicators

0 stored signals · no KEV · 0 OTX pulses