CVE-2026-50267 is a medium-severity (CVSS 4.7) CWE-312 vulnerability in Steeltoe.Configuration.Abstractions. A fix is available for Steeltoe.Configuration.Abstractions — see the affected versions and patch details below.
Steeltoe: TLS private keys written to /tmp with default permissions, never deleted
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-50267.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-50267 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
Steeltoe.Configuration.AbstractionsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
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_SERVICESwith a MySQL or PostgreSQL service binding that includessslKeycredentials. - 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Steeltoe.Configuration.Abstractions | ≥ 4.0.0&&< 4.2.0 | 4.2.0dotnet add package Steeltoe.Configuration.Abstractions --version 4.2.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Steeltoe.Configuration.Abstractions, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Steeltoe.Configuration.Abstractions to 4.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-50267 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-50267 in your dependencies?
Find it across NuGet, including transitive dependencies.