CVE-2026-100349: kin-openapi openapi3filter: nil-pointer panic in ValidateResponse on a response header declared with content
kin-openapi is a Go project for handling OpenAPI files. Prior to 0.146.0, openapi3filter.ValidateResponse passes a nil response header schema to decodeValue when an OpenAPI document declares the header with content instead of schema. The document passes validation, but every response validation for the affected operation dereferences the nil schema and panics even when the response does not contain the declared header. Applications that ingest an untrusted specification can expose this as remote availability impact, while applications using only trusted local specifications still crash when the affected operation is exercised. This issue is fixed in version 0.146.0.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
kin-openapito a version that resolves this vulnerability.Fixed in 0.146.0
Event History
Frequently Asked Questions
Which deployments are exposed to remote exploitation?
Applications that ingest an untrusted OpenAPI specification can expose a remote availability impact. A specification that declares a response header using content rather than schema can trigger the panic when response validation runs for the affected operation.
Does the affected response need to include the problematic header?
No. The panic occurs for every response validation of the affected operation even when the response does not contain the declared header.
Are applications using only local, trusted specifications unaffected?
No. Trusted local specifications do not make the affected operation safe: the application can still crash when that operation is exercised if its document contains the problematic header declaration.
What version fixes the issue?
The issue is fixed in kin-openapi version 0.146.0. Versions prior to 0.146.0 are affected.