CVE-2026-100347: Input Validation Flaw (CVSS 5.3)

Description

kin-openapi is a Go project for handling OpenAPI files. Prior to 0.145.0, openapi3filter.ValidationHandler uses the routers/legacy router, which passes an unsupported or non-canonical HTTP method for an existing static path to openapi3.PathItem.GetOperation. The default branch of GetOperation panics before authentication runs, so an unauthenticated remote client can repeatedly send methods such as PROPFIND or lowercase get to abort connections and generate stack-trace log growth. The specific panic requires an exact static path; a concrete path matched only by a templated route does not reach the same sink. This issue is fixed in version 0.145.0.

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CVSS v3.1 Score

5.3

MEDIUM

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

Weakness Type (CWE)

CWE-20 Improper Input Validation

CWE-248 CWE-248

References

Other References

https://github.com/getkin/kin-openapi/commit/f1a5b523b82868d2d9be2e116b4e942892be72c3 https://github.com/getkin/kin-openapi/releases/tag/v0.145.0 https://github.com/getkin/kin-openapi/security/advisories/GHSA-fh4f-47mf-f2gj https://github.com/getkin/kin-openapi/security/advisories/GHSA-fh4f-47mf-f2gj

Frequently Asked Questions

What is CVE-2026-100347? +

kin-openapi is a Go project for handling OpenAPI files. Prior to 0.145.0, openapi3filter.ValidationHandler uses the routers/legacy router, which passes an unsupported or non-canonical HTTP method for an existing static path to openapi3.PathItem.GetOperation. The default branch of GetOperation panics before authentication runs, so an unauthenticated remote client can repeatedly send methods such as PROPFIND or lowercase get to abort connections and generate stack-trace log growth. The specific panic requires an exact static path; a concrete path matched only by a templated route does not reach the same sink. This issue is fixed in version 0.145.0. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-100347? +

CVE-2026-100347 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-100347? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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