Auth bypass in Getkin Kin-Openapi
CVE-2026-73501
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.006 (46.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.006 · change: +0.002
Affected products
- Getkin Kin-Openapi — versions < 0.144.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-73501?
- CVE-2026-73501 is a critical-severity vulnerability in Getkin Kin-Openapi, classified under Improper Authentication. CVSS score: 9.1/10. Published 2026-08-12.
- How severe is CVE-2026-73501?
- Critical severity. CVSS v3 base score is 9.1 out of 10.