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CVE-2026-100353 high CVSS 7.5

Vulnerability in github.com/getkin/kin-openapi (CVE-2026-100353)

Summary

Vulnerability in github.com/getkin/kin-openapi (CVE-2026-100353). Risk of unauthorized operations or information disclosure. Exploitable via GET /test. Mitigation: upgrade to 0.149.0 or later.

Original description

The description as published by the source.

Summary

The fix for GHSA-p6wj-qrr4-pgh5 addressed a nil-pointer dereference that occurs when an OpenAPI 3.1 array schema omits the items keyword (which is legal under JSON Schema 2020-12). That fix patched three decoder paths: the standalone parseArray function, the top-level array check in UrlencodedBodyDecoder, and MultipartBodyDecoder.

Three additional crash paths were missed. All of them reach the unguarded urlValuesDecoder.parseArray method (openapi3filter/req_resp_decoder.go:576) or the unguarded array branch in buildResObj (line 1015):

  1. Query parameters with type: array and no items.
  2. deepObject query parameters containing an array property with no items.
  3. URL-encoded request bodies where the array lives inside an allOf / anyOf / oneOf sub-schema. This path bypasses the guard added by the GHSA-p6wj-qrr4-pgh5 fix, because that guard only inspects top-level properties.

Each path is triggerable by an unauthenticated client and produces a deterministic nil-pointer panic during request validation.

Details

Root Cause

The three paths patched for GHSA-p6wj-qrr4-pgh5 each received a nil-items guard:

// standalone parseArray (line 1143) -- GUARDED
func parseArray(raw []string, schemaRef *openapi3.SchemaRef) ([]any, error) {
	if schemaRef.Value.Items == nil || schemaRef.Value.Items.Value == nil { ... }

// UrlencodedBodyDecoder top-level property loop (line 1441) -- GUARDED
if propSchema.Value.Items == nil || pr…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-100353 has been found in github.com/getkin/kin-openapi.
Attackers can target a specific entry point like GET /test over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade github.com/getkin/kin-openapi to 0.149.0 or later.
If unsure, ask your IT team or search "github.com/getkin/kin-openapi CVE-2026-100353" on the vendor's site.

CVE-2026-100353 (github.com/getkin/kin-openapi) — CWE-476 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: GET /test / POST /submit / items / parseArray
Patched: 0.149.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-476) exists in github.com/getkin/kin-openapi. Attackers reach the vulnerable code path via GET /test without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/getkin/kin-openapi. Attack surface: GET /test / POST /submit / items / parseArray.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 0.149.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual GET /test requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/getkin/kin-openapi' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'github.com/getkin/kin-openapi' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で github.com/getkin/kin-openapi を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Hunt for indicators of compromise detect 
    grep 'GET /test' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで GET /test への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Apply patch patch 
    Upgrade github.com/getkin/kin-openapi to 0.149.0

    ステージング環境で 0.149.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。

  4. 4
    Post-deployment verification verify 
    Replay attack against GET /test on staging to confirm patch closes the vector

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

go github.com/getkin/kin-openapi
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.149.0"}]}]

References

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