How severe is CVE-2021-21428?

CVE-2021-21428 has a CVSS 3.x base score of 9.3, rated critical severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21428 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21428?

CVE-2021-21428 affects Openapi-generator Openapi Generator. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21428?

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

When was CVE-2021-21428 published?

CVE-2021-21428 was published on 2021-05-10 and last updated on 2026-06-17.

CVE-2021-21428

CVE-2021-21428 is a critical-severity vulnerability in Openapi-generator Openapi Generator with a CVSS 3.x base score of 9.3. 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-668.

Key facts

Severity: Critical (CVSS 3.x base score 9.3)
CVSS v2: 4.4
EPSS exploit prediction: 0% (27th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-668
Affected product: Openapi-generator Openapi Generator
Published: 2021-05-10
Last modified: 2026-06-17

Description

Openapi generator is a java tool which allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec. openapi-generator-online creates insecure temporary folders with File.createTempFile during the code generation process. The insecure temporary folders store the auto-generated files which can be read and appended to by any users on the system. The issue has been patched with `Files.createTempFile` and released in the v5.1.0 stable version.

Frequently asked questions

What is CVE-2021-21428?: Openapi generator is a java tool which allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec. openapi-generator-online creates insecure temporary folders with File.createTempFile during the code generation process. The insecure temporary folders store the auto-generated files which can be read and appended to by any users on the system. The issue has been patched with `Files.createTempFile` and released in the v5.1.0 stable version.
How severe is CVE-2021-21428?: CVE-2021-21428 has a CVSS 3.x base score of 9.3, rated critical severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21428 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21428?: CVE-2021-21428 affects Openapi-generator Openapi Generator. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21428?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-21428 published?: CVE-2021-21428 was published on 2021-05-10 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:openapi-generator:openapi_generator:*:*:*:*:*:*:*:*

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