# 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.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **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:** Yes
- **Published:** 17 Jun 2026
- **Updated:** 18 Jun 2026
- **Also known as:** GHSA-rxrh-4j9h-xgg9

## 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`.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource), CWE-312 (Cleartext Storage of Sensitive Information)

## Which versions are affected by CVE-2026-50267?

2 open source packages ship an affected version, including Steeltoe.Configuration.Abstractions.


| Package | Ecosystem | 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-50267 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-50267 in the wild and no public exploit code.

Affected packages and fixed versions:
- Steeltoe.Configuration.Abstractions (NuGet): affected from 4.0.0; fixed in 4.2.0
- Steeltoe.Configuration.Abstractions (NuGet): affected from 4.0.0; fixed in 4.2.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-50267/ (Markdown: https://insights.sbomify.com/CVE-2026-50267/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-50267
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-50267
- OSV: https://osv.dev/vulnerability/CVE-2026-50267

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-50267/
Summaries are generated and may contain mistakes; the official description above is the record.