Vulnerabilities in pkg:nuget/Steeltoe.Security.Authentication.OpenIdConnect

PACKAGE
Advisory Identifier: GHSA-7fqc-p256-7pwj
Advisory Summary

CVE-2026-50202 is a MODERATE (CVSS 5.9) steeltoe's static jwks cache shared vulnerability (CWE-668: Exposure of Resource to Wrong Sphere) affecting Steeltoe.Security.Authentication.JwtBearer libraries in the NuGet ecosystem. The issue involves steeltoe's static jwks cache shared across schemes and never invalidated. Remediation is available by upgrading affected packages to version 4.2.0, 3.4.0.

1 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:nuget/Steeltoe.Security.Authentication.OpenIdConnect

1 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:nuget/Steeltoe.Security.Authentication.OpenIdConnect. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-7fqc-p256-7pwj CVE-2026-50202 MODERATE Steeltoe's static JWKS cache shared across schemes and never invalidated

CVE-2026-50202 at a Glance

CVE Identifier CVE-2026-50202
GHSA Identifier GHSA-7fqc-p256-7pwj
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-668: Exposure of Resource to Wrong Sphere
Affected Product Steeltoe.Security.Authentication.JwtBearer
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 5.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required High (PR:H)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-50202

To remediate this vulnerability, upgrade all affected Steeltoe.Security.Authentication.JwtBearer dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Steeltoe.Security.Authentication.JwtBearer fixed: 4.2.0
Upgrade Steeltoe.Security.Authentication.JwtBearer to 4.2.0
Steeltoe.Security.Authentication.OpenIdConnect fixed: 4.2.0
Upgrade Steeltoe.Security.Authentication.OpenIdConnect to 4.2.0
Steeltoe.Security.Authentication.CloudFoundryBase fixed: 3.4.0
Upgrade Steeltoe.Security.Authentication.CloudFoundryBase to 3.4.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

inspect dependencies for Steeltoe.Security.Authentication.JwtBearer

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-50202, inspect your project dependencies for Steeltoe.Security.Authentication.JwtBearer:

inspect dependencies for Steeltoe.Security.Authentication.JwtBearer

Analyze the terminal output to locate any version of Steeltoe.Security.Authentication.JwtBearer in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.2.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-668: Exposure of Resource to Wrong Sphere, where the product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource. In Steeltoe.Security.Authentication.JwtBearer, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary 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. ### Impact In multi-scheme deployments, an attacker who controls one identity provider's signing key can forge tokens accepted by other schemes within the same application. For all applications using `TokenKeyResolver`, a signing key removed from the identity provider's JWKS endpoint remains trusted indefinitely. ### Mitigations If an immediate upgrade is not possible: - In multi-scheme deployments, configure only one `JwtBearer` scheme per application when different identity providers are required. - Restart the application process after an identity provider signing key rotation to clear stale cached keys.

CVE-2026-50202 Affected Steeltoe.Security.Authentication.JwtBearer Versions

3 component(s)
Fixed Versions:
4.2.03.4.0
Product / Package Ecosystem Affected Versions Fixed Version
Steeltoe.Security.Authentication.JwtBearer
NuGet
< 4.2.0
4.2.0
Steeltoe.Security.Authentication.OpenIdConnect
NuGet
< 4.2.0
4.2.0
Steeltoe.Security.Authentication.CloudFoundryBase
NuGet
< 3.4.0
3.4.0

References

Frequently Asked Questions

What is CVE-2026-50202?
CVE-2026-50202 is a security vulnerability in Steeltoe.Security.Authentication.JwtBearer involving Steeltoe's static JWKS cache shared across schemes and never invalidated under CWE-668: Exposure of Resource to Wrong Sphere.
Which Steeltoe.Security.Authentication.JwtBearer versions are affected?
Affected versions include releases prior to 4.2.0, 3.4.0 across affected packages: Steeltoe.Security.Authentication.JwtBearer, Steeltoe.Security.Authentication.OpenIdConnect, Steeltoe.Security.Authentication.CloudFoundryBase.
What version fixes CVE-2026-50202?
Upgrading to 4.2.0, 3.4.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Steeltoe.Security.Authentication.JwtBearer affected?
Yes, Steeltoe.Security.Authentication.JwtBearer is affected in releases prior to 4.2.0. Upgrade your dependency to 4.2.0 or later.
Is Steeltoe.Security.Authentication.OpenIdConnect affected?
Yes, Steeltoe.Security.Authentication.OpenIdConnect is affected in releases prior to 4.2.0. Upgrade your dependency to 4.2.0 or later.
What is the CVSS score of CVE-2026-50202?
CVE-2026-50202 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-50202?
CVE-2026-50202 is classified under CWE-668: Exposure of Resource to Wrong Sphere (The product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource.).
How can I check NuGet dependencies for CVE-2026-50202?
Run the dependency tree command: 'inspect dependencies for Steeltoe.Security.Authentication.JwtBearer'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7fqc-p256-7pwj",
  "modified" : "2026-07-02T20:31:47Z",
  "published" : "2026-07-02T20:31:47Z",
  "aliases" : [ "CVE-2026-50202" ],
  "summary" : "Steeltoe's static JWKS cache shared across schemes and never invalidated",
  "details" : "### Summary\n\nThe 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.\n\n### Impact\n\nIn multi-scheme deployments, an attacker who controls one identity provider's signing key can forge tokens accepted by other schemes within the same application. For all applications using `TokenKeyResolver`, a signing key removed from the identity provider's JWKS endpoint remains trusted indefinitely.\n\n### Mitigations\n\nIf an immediate upgrade is not possible:\n\n- In multi-scheme deployments, configure only one `JwtBearer` scheme per application when different identity providers are required.\n- Restart the application process after an identity provider signing key rotation to clear stale cached keys.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Steeltoe.Security.Authentication.JwtBearer"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.2.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.0"
    }
  }, {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Steeltoe.Security.Authentication.OpenIdConnect"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.2.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.0"
    }
  }, {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Steeltoe.Security.Authentication.CloudFoundryBase"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.4.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.3.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-7fqc-p256-7pwj"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-50202"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/Steeltoe/commit/04db2ace3b806bfe0260bb7d4bda340f241eff48"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/Steeltoe/commit/17b27b8be546ae3f83a2f6e91d45e0c84c5314b7"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/SteeltoeOSS/security-advisories"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-668" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-02T20:31:47Z",
    "nvd_published_at" : "2026-06-17T23:17:04Z"
  }
}