# CVE-2026-100347: kin-openapi: Unauthenticated denial of service in legacy router

Source: https://junglewise.ai/threats/cve-2026-100347-kin-openapi-unauthenticated-panic-dos-in-openapi3filter-legacy  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-15. Updated: 2026-10-15  
License: CC BY 4.0 with a link back

CVE-2026-100347 · Severity: medium · CVSS 5.3 · Published 2026-10-15

kin-openapi is a Go library that validates HTTP requests against OpenAPI specifications. An unauthenticated attacker can crash individual connection handlers by sending requests with non-standard or lowercase HTTP methods to any static path in the spec, causing the process to log unbounded error messages and reset connections before authentication is checked.

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

## Quick answers

**Is CVE-2026-100347 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100347 being exploited in the wild.

**How severe is CVE-2026-100347?** Medium severity, with a CVSS score of 5.3, published 15 October 2026.

**Which products and versions are affected?** github.com/getkin/kin-openapi (Go) <= 0.144.0, SEMVER:introduced=0,fixed=0.145.0; Kin-Openapi 0.144.0 and earlier.

**Is there a fix for CVE-2026-100347?** Yes. github.com/getkin/kin-openapi (Go): upgrade to 0.145.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-100347 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-100347?** Check whether you run github.com/getkin/kin-openapi (Go) or Kin-Openapi 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 0.145.0 or later

  ```sh
  go get github.com/getkin/kin-openapi@v0.145.0
  ```


## Technical details

The legacy router in openapi3filter matches request methods verbatim against a trie built only with uppercase canonical HTTP methods. Non-canonical methods (e.g., lowercase "get") or unsupported-but-valid tokens (e.g., "PROPFIND") miss the trie, and when targeting an existing static path, the code calls `PathItem.GetOperation()` with the unrecognized method, triggering a panic before authentication. Go's net/http recovers the per-connection panic, aborts the connection, and logs a stack trace; repeated requests cause log growth and availability degradation.

## Affected products

- kin-openapi kin-openapi 0.144.0 and earlier

## Identifiers

- CVE-2026-100347
- GHSA-fh4f-47mf-f2gj
- GO-2026-6783

## Timeline

- 2026-10-15: disclosed

## 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 nil pointer dereference in query/body array decoding](https://junglewise.ai/threats/cve-2026-100353-kin-openapi-incomplete-fix-for-ghsa-p6wj-qrr4-pgh5-three)