CVE-2026-100354
kin-openapi is a Go project for handling OpenAPI files.
Published Oct 15, 2026 · updated Oct 15, 2026
## Summary kin-openapi's spec loader and spec-time validator both handle circular schema references safely: the loader resolves circular s on purpose (to support recursive data structures), and uses stack-based cycle detection. therefore accepts a schema whose / / chain refers back to itself, returning no error. The runtime validators do not have that protection. When such a schema is used for request or response validation, the recursion through the combinator chain is unbounded. In Go this produces a **fatal stack overflow** ( / ), which is **not** a recoverable panic. cannot catch it, so 's per-connection recovery does not help. The entire process is terminated, including all goroutines serving unrelated clients. Two independent unguarded recursion sites were confirmed: 1. — / (reached by , i.e. response validation and direct schema validation). 2. — (reached first during request parameter decoding). The report also identifies the same gap in and / . ## Details ### Root Cause has cycle detection ( ): The runtime visitor has none. (line 1951) calls (line 2189), which iterates the combinator slice and calls again on each sub-schema: The request-decoding path has the same structure in ( ): ## Proof of Concept ### Environment - kin-openapi v0.144.0 (tag , commit ) - Go 1.26.7 ### Path A: response / direct schema validation ( ) A schema whose refers to itself. is called first to show the schema is accepted, then : Output: A placed around the call did **not** catch the fatal error — the process aborted with a non-zero exit code, confirming it is unrecoverable. ### Path B: HTTP request validation against a loaded spec (realistic delivery) A legal OAS 3.0 spec with a circular , loaded normally, served behind a standard handler using : A single crashes the whole server process: The line printed after the request ("the process survived") was never reached, and the process exited with a non-zero code — the standard per-connection did not save it. This is the key distinction
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Oct 15, 2026 · NIST NVD
Detected
kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON
Oct 15, 2026 · NIST NVD
Updated
kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON
Oct 15, 2026 · NIST NVD
Updated
kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON
Oct 15, 2026 · GitHub Advisory Database
Updated
## Summary kin-openapi's spec loader and spec-time validator both handle circular schema references safely: the loader resolves circular s on purpose (to support recursive data structures), and uses stack-based cycle detection. therefore accepts a schema whose / / chain refers back to itself, returning no error. The runtime validators do not have that protection. When such a schema is used for req
Affected
- go github.com/getkin/kin-openapi< 0.149.0
- go github.com/getkin/kin-openapi<0.149.0
- golang github.comversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2026-100354
Official CVE identifier
cve.org - GitHub Advisory DatabasePackage advisoryGHSA-g8cf-rcjf-c8cf
kin-openapi: Uncontrolled Recursion on Circular allOf/anyOf/oneOf Schemas Causes Fatal Process Crash
github.com - GitLab Advisory DatabasePackage advisoryCVE-2026-100354
kin-openapi's spec loader and spec-time validator both handle circular schema references safely: the loader resolves circular $refs on purpose (to support recursive data structures), and Schema.validate() uses stack-based cycle detection. Validate() therefore accepts a schema whose allOf / anyOf / oneOf chain refers back to itself, returning no error. The runtime validators do not have that protec
advisories.gitlab.com - GitLab Advisory DatabasePackage advisorygo/github.com/getkin/kin-openapi/CVE-2026-100354.yml
kin-openapi's spec loader and spec-time validator both handle circular + schema references safely: the loader resolves circular s on purpose (to support + recursive data structures), and uses stack-based cycle detection. + therefore accepts a schema whose / / chain + refers back to itself, returning no error.\n\nThe runtime validators do not have + that protection. When such a schema is used for r
gitlab.com - NIST NVDVulnerability recordCVE-2026-100354
kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the c
nvd.nist.gov