# CVE-2026-50202: Steeltoe's static JWKS cache shared across schemes and never invalidated > Attackers can bypass authentication in multi-scheme apps by exploiting shared JWT key caches that lack authority namespacing and expiration. - **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N`) - **Exploited in the wild:** Not known - **Login needed:** An administrator - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 17 Jun 2026 - **Updated:** 18 Jun 2026 - **Also known as:** GHSA-7fqc-p256-7pwj ## What is CVE-2026-50202? CVE-2026-50202 is a medium-severity authentication bypass vulnerability in SteeltoeOSS Steeltoe.Security.Authentication.CloudFoundryBase, published on 17 Jun 2026. An attacker needs administrator access to exploit it, with no action from the victim. ### Official description 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. Weakness: CWE-668 (Exposure of Resource to Wrong Sphere) ## Which versions are affected by CVE-2026-50202? 6 open source packages ship an affected version, including Steeltoe.Security.Authentication.CloudFoundryBase, Steeltoe.Security.Authentication.JwtBearer and Steeltoe.Security.Authentication.OpenIdConnect. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `Steeltoe.Security.Authentication.CloudFoundryBase` | NuGet | All versions | 3.4.0 | | `Steeltoe.Security.Authentication.CloudFoundryBase` | NuGet | All versions | 3.4.0 | | `Steeltoe.Security.Authentication.JwtBearer` | NuGet | All versions | 4.2.0 | | `Steeltoe.Security.Authentication.JwtBearer` | NuGet | All versions | 4.2.0 | | `Steeltoe.Security.Authentication.OpenIdConnect` | NuGet | All versions | 4.2.0 | | `Steeltoe.Security.Authentication.OpenIdConnect` | NuGet | All versions | 4.2.0 | ## How do I fix CVE-2026-50202? Upgrade Steeltoe.Security.Authentication.CloudFoundryBase to 3.4.0 or later. ## Is CVE-2026-50202 being exploited? There is no known exploitation of CVE-2026-50202 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-50202 and fix it if it is affected. What it is: CVE-2026-50202 is a medium-severity authentication bypass vulnerability in SteeltoeOSS Steeltoe.Security.Authentication.CloudFoundryBase, published on 17 Jun 2026. An attacker needs administrator access to exploit it, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-50202 in the wild and no public exploit code. Affected packages and fixed versions: - Steeltoe.Security.Authentication.CloudFoundryBase (NuGet): affected all versions; fixed in 3.4.0 - Steeltoe.Security.Authentication.CloudFoundryBase (NuGet): affected all versions; fixed in 3.4.0 - Steeltoe.Security.Authentication.JwtBearer (NuGet): affected all versions; fixed in 4.2.0 - Steeltoe.Security.Authentication.JwtBearer (NuGet): affected all versions; fixed in 4.2.0 - Steeltoe.Security.Authentication.OpenIdConnect (NuGet): affected all versions; fixed in 4.2.0 - Steeltoe.Security.Authentication.OpenIdConnect (NuGet): affected all versions; fixed in 4.2.0 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-50202/ (Markdown: https://insights.sbomify.com/CVE-2026-50202/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-50202 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-50202 - OSV: https://osv.dev/vulnerability/CVE-2026-50202 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-50202/ Summaries are generated and may contain mistakes; the official description above is the record.