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.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
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 | 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.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-50202 being exploited?
There is no known exploitation of CVE-2026-50202 in the wild and no public exploit code.
Sources
Also known as GHSA-7fqc-p256-7pwj.