CVE-2026-50267 Steeltoe: TLS private keys written to /tmp with default permissions, never deleted
An attacker with local access can read TLS private keys from world-readable temporary files created by Steeltoe libraries.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-50267?
CVE-2026-50267 is a medium-severity vulnerability in SteeltoeOSS Steeltoe.Configuration.Abstractions, published on 17 Jun 2026. It can only be exploited from the same machine or local network, 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.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`.
Which versions are affected by CVE-2026-50267?
2 open source packages ship an affected version, including Steeltoe.Configuration.Abstractions.
| Package | Affected | Fixed in |
|---|---|---|
Steeltoe.Configuration.Abstractions NuGet | From 4.0.0 | 4.2.0 |
Steeltoe.Configuration.Abstractions NuGet | From 4.0.0 | 4.2.0 |
How do I fix CVE-2026-50267?
Upgrade Steeltoe.Configuration.Abstractions to 4.2.0 or later.
Is CVE-2026-50267 being exploited?
There is no known exploitation of CVE-2026-50267 in the wild and no public exploit code.
Sources
Also known as GHSA-rxrh-4j9h-xgg9.