kin-openapi spec loader panics on a self-referential additionalProperties $ref (nil-pointer DoS)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-100348: 0.37% estimated exploitation activity in the next 30 days; percentile 31.16 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

The defect ---------- Confirmed at HEAD (f0407d5, v0.144.0). openapi3/loader.go, inside resolveComponent's drill closure (around line 455), the case SchemaRef branch for pathPart == "additionalProperties" dereferences c.Value.AdditionalProperties with no nil-check on c.Value: case SchemaRef: if pathPart == "additionalProperties" { if ap := c.Value.AdditionalProperties.Has; ap != nil { // c.Value can be nil here cursor = ap } else { cursor = c.Value.AdditionalProperties.Schema } attempted = true } When a $ref fragment drills through .../additionalProperties of a schema whose Value is still nil (a pure, not-yet-resolved $ref, or a self-reference resolved before its own Value is set), c.Value is nil and the .AdditionalProperties access panics. Input and attacker ------------------- A tiny crafted OpenAPI document, one schema, no external refs, no network: openapi: 3.0.3 info: {title: t, version: "1.0.0"} paths: {} components: schemas: A: $ref:…

Published by the source

15 Oct 2026, 20:15 UTC

Last modified by the source

15 Oct 2026, 20:30 UTC

Source last checked

26 Oct 2026, 15:32 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mh7x-f8wq-4jhx

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mh7x-f8wq-4jhx

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# Patch Next advisory brief: CVE-2026-100348

Advisory: kin-openapi spec loader panics on a self-referential additionalProperties $ref (nil-pointer DoS)
IDs: CVE-2026-100348, GHSA-mh7x-f8wq-4jhx
Record: https://patchnext.com/advisories/cve-2026-100348 (revision 2, source checked 26 Oct 2026, 15:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/getkin/kin-openapi 0.145.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/getkin/kin-openapi: affected <= 0.144.0; fixed in 0.145.0

## Suggested inspection (read-only)
- Go github.com/getkin/kin-openapi: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/getkin/kin-openapi.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-mh7x-f8wq-4jhx (OSV record GHSA-mh7x-f8wq-4jhx lists affected ranges: Go github.com/getkin/kin-openapi >=0 <0.145.0 (fixed))
- Verified: https://github.com/advisories/GHSA-mh7x-f8wq-4jhx (GitHub-reviewed advisory GHSA-mh7x-f8wq-4jhx lists affected ranges: Go github.com/getkin/kin-openapi >=0 <=0.144.0)

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