Vulnerability in Steeltoe.Security.Authentication.JwtBearer (CVE-2026-50202)
Summary
Vulnerability in Steeltoe.Security.Authentication.JwtBearer (CVE-2026-50202). Confidential information can be exposed externally. Exploitable via TokenKeyResolver. Mitigation: upgrade to 4.2.0 or later.
Original description
The description as published by the source.
Steeltoe is an open source project that provides a collection of libraries that helps users build cloud-native applications. In Steeltoe.Security.Authentication.CloudFoundryBase prior to version 3.4.0, Steeltoe.Security.Authentication.JwtBearer prior to version 4.2.0, and Steeltoe.Security.Authentication.OpenIdConnect prior to version 4.2.0, the JWT signing key cache in TokenKeyResolver uses kid as the sole cache key without namespacing by authority. In applications with multiple JwtBearer schemes pointing to different identity providers, a key fetched for one scheme can satisfy token validation for another. Additionally, cached keys have no expiration, so rotated or revoked keys remain trusted until the application process restarts. Steeltoe.Security.Authentication.CloudFoundryBase version 3.4.0, Steeltoe.Security.Authentication.JwtBearer version 4.2.0, and Steeltoe.Security.Authentication.OpenIdConnect version 4.2.0 patch the issue. If an immediate upgrade is not possible: In multi-scheme deployments, configure only one JwtBearer scheme per application when different identity providers are required; and/or restart the application process after an identity provider signing key rotation to clear stale cached keys.
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-2026-50202 has been found in Steeltoe.Security.Authentication.JwtBearer.
Attackers can target a specific entry point like TokenKeyResolver over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 5.9/10.
What to do: upgrade Steeltoe.Security.Authentication.JwtBearer to 4.2.0 or later.
If unsure, ask your IT team or search "Steeltoe.Security.Authentication.JwtBearer CVE-2026-50202" on the vendor's site.
CVE-2026-50202 (Steeltoe.Security.Authentication.JwtBearer) — CWE-668 / CVSS v3 5.9
Attack vector: remote (network-reachable) / no user interaction
Attack surface: TokenKeyResolver / kid / JwtBearer
Patched: 4.2.0 — 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.
A vulnerability (CWE-668) exists in Steeltoe.Security.Authentication.JwtBearer. Attackers reach the vulnerable code path via TokenKeyResolver.
Check the vendor advisory for the affected versions of Steeltoe.Security.Authentication.JwtBearer. Attack surface: TokenKeyResolver / kid / JwtBearer.
Severity: Medium (CVSS 5.9/10). Confidential information can be exposed externally.
Update to 4.2.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Steeltoe.Security.Authentication.JwtBearer' . 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
-
1Identify exposure identify
grep -r 'Steeltoe.Security.Authentication.JwtBearer' . | 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.Authentication.JwtBearerを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Steeltoe.Security.Authentication.JwtBearer to 4.2.0ステージング環境で 4.2.0 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。
-
3Post-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
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- patch github.com
- patch github.com
- web github.com