How severe is CVE-2021-22955?

CVE-2021-22955 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-22955 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-22955?

CVE-2021-22955 primarily affects Citrix Gateway. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-22955?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-22955 published?

CVE-2021-22955 was published on 2021-12-07 and last updated on 2026-06-17.

CVE-2021-22955

CVE-2021-22955 is a high-severity vulnerability in Citrix Gateway with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Citrix Gateway
Published: 2021-12-07
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-22955?: CVE-2021-22955 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-22955 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-22955?: CVE-2021-22955 primarily affects Citrix Gateway. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-22955?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-22955 published?: CVE-2021-22955 was published on 2021-12-07 and last updated on 2026-06-17.

References

https://support.citrix.com/article/CTX330728

Affected products (2)

cpe:2.3:o:citrix:application_delivery_controller_firmware:*:*:*:*:*:*:*:*
cpe:2.3:a:citrix:gateway:*:*:*:*:*:*:*:*

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CVE-2022-27510 — Critical (CVSS 9.8): Unauthorized access to Gateway user capabilities
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