GHSA-rxrh-4j9h-xgg9 Steeltoe: TLS private keys written to /tmp with default permissions, never deleted

• NuGet Steeltoe.Configuration.Abstractions: >= 4.0.0, < 4.2.0 → fixed in 4.2.0

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//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`.