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Critical

kin-openapi: ValidationHandler.Load() Fail-Open Authentication Bypass via NoopAuthenticationFunc Default

Type: advisorySources: OSV

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-73501
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 23:59 UTC · Revision 1

Source evidence

kin-openapi: ValidationHandler.Load() Fail-Open Authentication Bypass via NoopAuthenticationFunc Default

core-osv · Original source

Published 12 Aug 2026, 21:23 UTC

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.

osv:CVE-2026-73501
Complete source record
{
  "id": "da406cceefc94488106287758c85e6180639d173c9ef7f45eb729557a02721dc",
  "url": "https://osv.dev/vulnerability/CVE-2026-73501",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "kin-openapi: ValidationHandler.Load() Fail-Open Authentication Bypass via NoopAuthenticationFunc Default",
    "summary": "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.",
    "evidence": "osv:CVE-2026-73501",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-73501",
      "aliases": [
        "CVE-2026-73501",
        "GHSA-r277-6w6q-xmqw",
        "GO-2026-6095"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
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              "repo": "https://github.com/getkin/kin-openapi",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
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                {
                  "fixed": "f0407d53b0730280266f454b755010e7eeb985da"
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              "database_specific": {
                "extracted_events": [
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                    "range": [
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                        "introduced": "0"
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                      {
                        "fixed": "0.144.0"
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                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "f0407d53b0730280266f454b755010e7eeb985da"
                      }
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                    "source": "REFERENCES_COMMIT"
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                    "range": [
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                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.144.0"
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                  {
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                    "source": "DESCRIPTION"
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          "database_specific": {
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      ],
      "modified": "2026-10-28T02:30:40.457163045Z",
      "provider": "osv",
      "references": [
        "https://github.com/getkin/kin-openapi/releases/tag/v0.144.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73501.json",
        "https://github.com/getkin/kin-openapi/security/advisories/GHSA-r277-6w6q-xmqw",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-73501",
        "https://github.com/getkin/kin-openapi/commit/f0407d53b0730280266f454b755010e7eeb985da"
      ],
      "provider_metadata": {
        "cwe_ids": [
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        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73501.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-73501",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 508202,
  "published_at": "2026-08-12T21:23:40.623+00:00"
}