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CVE-2026-81868 medium CVSS 6.5

Vulnerability in Steeltoe.Security.Authorization.Certificate (CVE-2026-81868)

Summary

Vulnerability in Steeltoe.Security.Authorization.Certificate (CVE-2026-81868). Confidential information can be exposed externally. Exploitable via UseCertificateAuthorization. Mitigation: upgrade to 4.3.0 or later.

Original description

The description as published by the source.

Summary

When Steeltoe's certificate-based authorization (UseCertificateAuthorization) is configured, the default configuration of the middleware relies on the X-Client-Cert HTTP header to identify the client certificate, without verifying private-key possession. This header is not stripped by common Cloud Foundry routers (like Gorouter or Envoy) on inbound requests.

Impact

An attacker who obtains the public certificate of an application instance in the target organization or space can spoof the X-Client-Cert header. This allows the attacker to bypass SameOrg and SameSpace authorization policies, granting unauthorized access to protected endpoints for the duration of the certificate's validity period.

Affected configuration

  • The application uses AddOrgAndSpacePolicies() and UseCertificateAuthorization() for inter-service authorization.
  • Inbound requests are not restricted to a known trusted proxy source IP.
  • The application's endpoints are network-accessible to the attacker (e.g., exposed to the internet via a public Cloud Foundry route, or the attacker has access to the internal Cloud Foundry network).

Mitigations

If an immediate upgrade to a patched version is not possible:

  • Restrict UseCertificateForwarding to trusted proxy source IPs using ForwardedHeadersOptions.KnownProxies and KnownNetworks.
  • Change the forwarding header to X-Forwarded-Client-Cert so that Cloud Foundry Gorouter and Envoy header stripping mechanisms appl…

Source: NIST National Vulnerability Database 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-2026-81868 has been found in Steeltoe.Security.Authorization.Certificate.
Attackers can target a specific entry point like UseCertificateAuthorization over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 6.5/10.
What to do: upgrade Steeltoe.Security.Authorization.Certificate to 4.3.0 or later.
If unsure, ask your IT team or search "Steeltoe.Security.Authorization.Certificate CVE-2026-81868" on the vendor's site.

CVE-2026-81868 (Steeltoe.Security.Authorization.Certificate) — CWE-288 / CVSS v3 6.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: UseCertificateAuthorization / SameOrg / SameSpace / UseCertificateForwarding
Patched: 4.3.0 — 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-288) exists in Steeltoe.Security.Authorization.Certificate. Attackers reach the vulnerable code path via UseCertificateAuthorization without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of Steeltoe.Security.Authorization.Certificate. Attack surface: UseCertificateAuthorization / SameOrg / SameSpace / UseCertificateForwarding.

🔥 Severity

Severity: Medium (CVSS 6.5/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 4.3.0.

🛡️ 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 request patterns matching this CVE's known IOCs. Run grep -r 'Steeltoe.Security.Authorization.Certificate' . 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 'Steeltoe.Security.Authorization.Certificate' . | 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 Steeltoe.Security.Authorization.Certificate 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
    Apply patch patch 
    Upgrade Steeltoe.Security.Authorization.Certificate to 4.3.0

    ステージング環境で 4.3.0 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を含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    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。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

nuget Steeltoe.Security.Authorization.Certificate
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.3.0"}]}]

References

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