CVE-2026-50267: Steeltoe TLS Private Keys Written To Vulnerability

MODERATE
Advisory Identifier: GHSA-rxrh-4j9h-xgg9
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CVSS 4.7
CWE-312 CWE-732
Published
Advisory Summary

CVE-2026-50267 is a MODERATE (CVSS 4.7) tls private keys written to vulnerability (CWE-312: Cleartext Storage of Sensitive Information) affecting Steeltoe libraries in the NuGet ecosystem. The issue involves tls private keys written to /tmp with default permissions, never deleted. Remediation is available by upgrading affected packages to version 4.2.0.

CVE-2026-50267 at a Glance

CVE Identifier CVE-2026-50267
GHSA Identifier GHSA-rxrh-4j9h-xgg9
Severity MODERATE
CVSS v3.1 Base Score 4.7
CWE Classification CWE-312: Cleartext Storage of Sensitive Information
Affected Product Steeltoe
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 4.7

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

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

How to Fix CVE-2026-50267

To remediate this vulnerability, upgrade all affected Steeltoe 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.Configuration.Abstractions fixed: 4.2.0 
Upgrade Steeltoe.Configuration.Abstractions to 4.2.0
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.Configuration.Abstractions

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-50267, inspect your project dependencies for Steeltoe:

inspect dependencies for Steeltoe.Configuration.Abstractions

Analyze the terminal output to locate any version of Steeltoe 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-312: Cleartext Storage of Sensitive Information, where the product stores sensitive information in cleartext within a resource that might be accessible to another control sphere. In Steeltoe, 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 When MySQL or PostgreSQL service bindings from `VCAP_SERVICES` include TLS client credentials, the Connectors library writes those credentials to temporary files in `Path.GetTempPath()` using `File.CreateText`. On Linux, `File.CreateText` creates files with mode `0644` (world-readable) under the process umask, and the files are never deleted. The same key material is protected at mode `0400` in `/proc/<pid>/environ`. ### Impact Any process co-located in the container that runs as a different UID can read the TLS client private key from `/tmp` and use it to impersonate the application when connecting to the backing database over mutual TLS. ### Affected configuration - Application is deployed on Cloud Foundry or another environment that populates `VCAP_SERVICES` with a MySQL or PostgreSQL service binding that includes `sslKey` credentials. - A process running as a different UID shares the container's filesystem. ### Mitigations If an immediate upgrade is not possible, prevent other processes from running in the container under a different UID with access to `/tmp`.

CVE-2026-50267 Affected Steeltoe Versions

1 component(s)
Fixed Versions:
4.2.0
Product / Package Ecosystem Affected Versions Fixed Version
Steeltoe.Configuration.Abstractions
nuget/Steeltoe.Configuration.Abstractions
NuGet
≥ 4.0.0
< 4.2.0
4.2.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-rxrh-4j9h-xgg9
NVD — CVE-2026-50267 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-50267
Security Fix Commit FIX COMMIT
https://github.com/SteeltoeOSS/Steeltoe/commit/8dd97cc6c4b184121a4bd1f92f9ac16918433471
Steeltoe Source Repository REPOSITORY
https://github.com/SteeltoeOSS/security-advisories

Frequently Asked Questions

What is CVE-2026-50267?
CVE-2026-50267 is a security vulnerability in Steeltoe involving TLS private keys written to /tmp with default permissions, never deleted under CWE-312: Cleartext Storage of Sensitive Information.
Which Steeltoe versions are affected?
Affected versions include releases prior to 4.2.0 across affected packages: Steeltoe.Configuration.Abstractions.
What version fixes CVE-2026-50267?
Upgrading to 4.2.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Steeltoe.Configuration.Abstractions affected?
Yes, Steeltoe.Configuration.Abstractions 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-2026-50267?
CVE-2026-50267 has a CVSS v3.1 base score of 4.7 (MODERATE) with vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-50267?
CVE-2026-50267 is classified under CWE-312: Cleartext Storage of Sensitive Information (The product stores sensitive information in cleartext within a resource that might be accessible to another control sphere.).
How can I check NuGet dependencies for CVE-2026-50267?
Run the dependency tree command: 'inspect dependencies for Steeltoe.Configuration.Abstractions'. 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
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rxrh-4j9h-xgg9",
  "modified" : "2026-07-02T20:32:09Z",
  "published" : "2026-07-02T20:32:09Z",
  "aliases" : [ "CVE-2026-50267" ],
  "summary" : "Steeltoe: TLS private keys written to /tmp with default permissions, never deleted",
  "details" : "### Summary\n\nWhen MySQL or PostgreSQL service bindings from `VCAP_SERVICES` include TLS client credentials, the Connectors library writes those credentials to temporary files in `Path.GetTempPath()` using `File.CreateText`. On Linux, `File.CreateText` creates files with mode `0644` (world-readable) under the process umask, and the files are never deleted. The same key material is protected at mode `0400` in `/proc/<pid>/environ`.\n\n### Impact\n\nAny process co-located in the container that runs as a different UID can read the TLS client private key from `/tmp` and use it to impersonate the application when connecting to the backing database over mutual TLS.\n\n### Affected configuration\n\n- Application is deployed on Cloud Foundry or another environment that populates `VCAP_SERVICES` with a MySQL or PostgreSQL service binding that includes `sslKey` credentials.\n- A process running as a different UID shares the container's filesystem.\n\n### Mitigations\n\nIf an immediate upgrade is not possible, prevent other processes from running in the container under a different UID with access to `/tmp`.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "Steeltoe.Configuration.Abstractions"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.2.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-rxrh-4j9h-xgg9"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-50267"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SteeltoeOSS/Steeltoe/commit/8dd97cc6c4b184121a4bd1f92f9ac16918433471"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/SteeltoeOSS/security-advisories"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-312", "CWE-732" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-02T20:32:09Z",
    "nvd_published_at" : "2026-06-17T23:17:04Z"
  }
}