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CVE-2026-100352 high CVSS 7.5

Vulnerability in github.com/getkin/kin-openapi (CVE-2026-100352)

Summary

Vulnerability in github.com/getkin/kin-openapi (CVE-2026-100352). Risk of unauthorized operations or information disclosure. Exploitable via POST /test. Mitigation: upgrade to 0.148.0 or later.

Original description

The description as published by the source.

Summary

kin-openapi guards against NaN and Inf values in its built-in schema visitor (visitJSON) by returning ErrSchemaInputNaN / ErrSchemaInputInf when a float64 input violates those constraints. For OAS 3.1 specs, however, Schema.VisitJSON routes through useJSONSchema2020, which hands the value directly to santhosh-tekuri/jsonschema/v6 v6.0.2 without applying the same guard.

Inside jsonschema/v6 v6.0.2, numValidate builds a *big.Rat from the input via big.Rat.SetString(fmt.Sprintf("%v", v)). For NaN/Inf this parse fails silently and returns nil. numValidate then dereferences the nil *big.Rat (in math/big.(*Rat).Cmp), producing a Go runtime panic.

An attacker delivers this by sending an HTTP request with Content-Type: application/yaml (or application/x-yaml) and a YAML body containing .nan, .inf, or -.inf. The YamlBodyDecoder decodes those tokens into math.NaN() / math.Inf(±1) (standard YAML 1.2 behavior), and they propagate to the unguarded useJSONSchema2020 path whenever the schema declares a numeric constraint (minimum, maximum, exclusiveMinimum, exclusiveMaximum, or multipleOf).

Details

Root Cause

The built-in visitor visitJSON at openapi3/schema.go:1968 guards NaN/Inf explicitly:

case float64:
    if math.IsNaN(value) {
        return ErrSchemaInputNaN
    }
    if math.IsInf(value, 0) {
        return ErrSchemaInputInf
    }

For OAS 3.1 specs, VisitJSON dispatches to `use…

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-2026-100352 has been found in github.com/getkin/kin-openapi.
Attackers can target a specific entry point like POST /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 0.148.0 or later.
If unsure, ask your IT team or search "github.com/getkin/kin-openapi CVE-2026-100352" on the vendor's site.

CVE-2026-100352 (github.com/getkin/kin-openapi) — CWE-754 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /test / NaN / Inf / visitJSON
Patched: 0.148.0 — 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-754) exists in github.com/getkin/kin-openapi. Attackers reach the vulnerable code path via POST /test without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/getkin/kin-openapi. Attack surface: POST /test / NaN / Inf / visitJSON.

🔥 Severity

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

🔧 How to fix

Update to 0.148.0.

🛡️ 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 POST /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 'POST /test' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /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 0.148.0

    ステージング環境で 0.148.0 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 POST /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":"0.148.0"}]}]

References

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