CVE-2026-73501 kin-openapi: ValidationHandler.Load() Fail-Open Authentication Bypass via NoopAuthenticationFunc Default
Attackers can bypass authentication in applications using kin-openapi's ValidationHandler due to a default no-op authentication function, allowing unauthorized access to protected endpoints.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-73501?
CVE-2026-73501 is a critical authentication bypass vulnerability in getkin kin-openapi, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-287
Which versions are affected by CVE-2026-73501?
3 open source packages ship an affected version, including github.com/getkin/kin-openapi.
| Package | Affected | Fixed in |
|---|---|---|
github.com/getkin/kin-openapi Go | All versions | 0.144.0 |
github.com/getkin/kin-openapi Go | All versions | 0.144.0 |
github.com/getkin/kin-openapi Go | All versions | 0.144.0 |
Linux distribution packages (1)
grafana13.1 Red Hat:hummingbird:1 | All versions | 0:13.1.3-0.2.hum1 |
How do I fix CVE-2026-73501?
Upgrade github.com/getkin/kin-openapi to 0.144.0 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-73501 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73501 exists.
Sources
Also known as CLEANSTART-2026-FW53154, CLEANSTART-2026-MA90195, CLEANSTART-2026-YF58790, DEBIAN-CVE-2026-73501, GHSA-r277-6w6q-xmqw, GO-2026-6095 and 47 more.