# CVE-2026-73501: getkin kin-openapi authentication bypass in ValidationHandler

Source: https://junglewise.ai/threats/cve-2026-73501-getkin-kin-openapi-authentication-bypass-in-validationhandler  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-12. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-73501 · Severity: critical · CVSS 9.1 · Published 2026-08-12

kin-openapi is a Go library for parsing and validating OpenAPI specifications. Applications using it to enforce API security can be bypassed—unauthenticated requests will pass security checks if the application fails to configure an authentication function, allowing attackers to access protected endpoints without valid credentials.

Technologies: [Getkin Kin-Openapi](https://junglewise.ai/threats/technologies/kin-openapi), [github.com/getkin/kin-openapi (Go)](https://junglewise.ai/threats/technologies/github-com-getkin-kin-openapi). Vendors: [Getkin](https://junglewise.ai/threats/vendors/getkin), [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-73501 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-73501 being exploited in the wild.

**How severe is CVE-2026-73501?** Critical severity, with a CVSS score of 9.1, published 12 August 2026.

**Which products and versions are affected?** Getkin Kin-Openapi before 0.144.0; github.com/getkin/kin-openapi (Go) SEMVER:introduced=0,fixed=0.144.0.

**Is there a fix for CVE-2026-73501?** Yes. github.com/getkin/kin-openapi (Go): upgrade to 0.144.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-73501 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-73501?** Check whether you run Getkin Kin-Openapi or github.com/getkin/kin-openapi (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/getkin/kin-openapi (Go): upgrade to 0.144.0 or later

  ```sh
  go get github.com/getkin/kin-openapi@v0.144.0
  ```


## Technical details

The vulnerability is an authentication bypass in ValidationHandler.Load() (openapi3filter/validation_handler.go) that silently substitutes a nil AuthenticationFunc with NoopAuthenticationFunc, which unconditionally returns nil without verifying credentials. This prevents the fail-closed ErrAuthenticationServiceMissing error path from being triggered, causing all OpenAPI security requirements to be satisfied for unauthenticated requests. Affected applications must have configured ValidationHandler as their enforcement middleware and failed to provide a custom authentication function. An attacker can send requests without authentication credentials to bypass API key, OAuth token, or other configured security schemes. The issue is resolved in version 0.144.0.

## Affected products

- getkin kin-openapi before 0.144.0

## Identifiers

- CVE-2026-73501
- GHSA-r277-6w6q-xmqw
- GO-2026-6095

## Timeline

- 2026-08-12: disclosed
- 2026-07-23: patched: Fixed in version 0.144.0

## References

- [https://github.com/getkin/kin-openapi/commit/f0407d53b0730280266f454b755010e7eeb985da](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/releases/tag/v0.144.0)

## Related threats

- [kin-openapi uncontrolled recursion on circular allOf/anyOf/oneOf schemas](https://junglewise.ai/threats/cve-2026-100354-kin-openapi-uncontrolled-recursion-on-circular-allof-anyof-oneof)
- [kin-openapi SecurityHandler authentication bypass via path encoding](https://junglewise.ai/threats/cve-2026-100351-kin-openapi-validationhandler-security-requirement-bypass-via)
- [kin-openapi deepObject query decoding DoS via repeated regexp compilation](https://junglewise.ai/threats/cve-2026-100350-kin-openapi-deepobject-query-decoding-repeatedly-compiles-an)
- [kin-openapi OpenAPI spec loader nil-pointer panic on self-referential additionalProperties](https://junglewise.ai/threats/cve-2026-100348-kin-openapi-spec-loader-panics-on-a-self-referential)
- [kin-openapi: Unauthenticated denial of service in legacy router](https://junglewise.ai/threats/cve-2026-100347-kin-openapi-unauthenticated-panic-dos-in-openapi3filter-legacy)