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Vulnerability record · CVE-2026-73501 · published 12 August 2026

CVE-2026-73501: Improper authentication vulnerability

kin-openapi is a Go project for handling OpenAPI files. Prior to 0.144.0, ValidationHandler.Load() in openapi3filter/validation_handler.go silently replaces a nil AuthenticationFunc with NoopAuthenticationFunc, which returns nil without checking credentials. This substitution causes every OpenAPI security requirement to be satisfied for unauthenticated requests when an application relies on ValidationHandler as its enforcement middleware. The no-op callback prevents the fail-closed ErrAuthenticationServiceMissing path from being reached and forwards the request to protected handlers that may require an API key, OAuth token, or another security scheme. This issue is fixed in version 0.144.0.

9.1 CVSS 3.1 Critical EPSS 0.59% · top 54.0% CWE-287 · Improper authentication Deferred
9.1CVSS 3.1 base score
0.59%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
18 Sep 2026Last modified by NVD

Description

kin-openapi is a Go project for handling OpenAPI files. Prior to 0.144.0, ValidationHandler.Load() in openapi3filter/validation_handler.go silently replaces a nil AuthenticationFunc with NoopAuthenticationFunc, which returns nil without checking credentials. This substitution causes every OpenAPI security requirement to be satisfied for unauthenticated requests when an application relies on ValidationHandler as its enforcement middleware. The no-op callback prevents the fail-closed ErrAuthenticationServiceMissing path from being reached and forwards the request to protected handlers that may require an API key, OAuth token, or another security scheme. This issue is fixed in version 0.144.0.

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

References

LinkTags
https://github.com/getkin/kin-openapi/commit/f0407d53b0730280266f454b755010e7eeb985da
https://github.com/getkin/kin-openapi/releases/tag/v0.144.0
https://github.com/getkin/kin-openapi/security/advisories/GHSA-r277-6w6q-xmqw
https://github.com/getkin/kin-openapi/security/advisories/GHSA-r277-6w6q-xmqw

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Source: NIST National Vulnerability Database (record CVE-2026-73501), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.