CVE-2026-76905: kin-openapi openapi3filter nil-pointer panic in ConvertErrors

CVE-2026-76905 · Severity: high · CVSS 7.5 · Published 2026-08-21

The kin-openapi library's error-rendering component crashes when processing malformed multipart form submissions with invalid scalar values. Any unauthenticated user can trigger a denial-of-service by sending a single crafted HTTP request to an endpoint that accepts multipart form data and uses the library's standard error handler. The crash aborts the request handler, and repeated attacks prevent the service from handling legitimate traffic.

Technologies: Getkin Kin-Openapi, github.com/getkin/kin-openapi (Go). Vendors: Getkin, Go.

Quick answers

Is CVE-2026-76905 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-76905 being exploited in the wild.
How severe is CVE-2026-76905?
High severity, with a CVSS score of 7.5, published 21 August 2026.
Which products and versions are affected?
Getkin Kin-Openapi 0.10.0 through 0.140.0; github.com/getkin/kin-openapi (Go) >= 0.10.0, < 0.141.0, SEMVER:introduced=0.10.0,fixed=0.141.0.
Is there a fix for CVE-2026-76905?
Yes. github.com/getkin/kin-openapi (Go): upgrade to 0.141.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-76905 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-76905?
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 0.141.0 or later
    go get github.com/getkin/kin-openapi@v0.141.0

Technical details

The vulnerability exists in the convertParseError function at openapi3filter/validation_error_encoder.go:119-120, where the code dereferences e.Parameter.In without first checking if e.Parameter is nil. This occurs only when processing multipart/form-data bodies because the multipart decoder wraps ParseError objects inside other ParseError objects (nested), causing a type assertion to succeed and execution to reach the unsafe dereference. In contrast, JSON parsing paths either fail the type assertion (JSON syntax errors) or route to a different handler (schema violations). The precondition for exploitation requires an endpoint accepting multipart/form-data with at least one non-string scalar property, and that the application use the library's ValidationErrorEncoder or ConvertErrors helper to format validation responses. No authentication or special privileges are required. The recommended fix is a one-line nil guard: change the condition to include `e.Parameter != nil` before accessing `e.Parameter.In`.

Affected products

  • getkin kin-openapi 0.10.0 through 0.140.0

Identifiers

  • CVE-2026-76905
  • GHSA-mmfr-pmjx-hw9w
  • GO-2026-6274

Timeline

  • 2026-07-10: disclosed
  • 2026-08-21: patched: Version 0.141.0 released with fix
  • 2026-08-21: advisory: GitHub Advisory Database published

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.