OpenTelemetry's disk retry default temp path enables local blob injection via OTLP Exporter — CVE-2026-42191

Summary

### Summary The OTLP disk retry feature in `OpenTelemetry.Exporter.OpenTelemetryProtocol` silently fell back to `Path.GetTempPath()` when `OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRY=disk` was set but `OTEL_DOTNET_EXPERIMENTAL_OTLP_DISK_RETRY_DIRECTORY_PATH` was not configured. The exporter stored and loaded `*.blob` files under fixed, signal-named subdirectories (`traces`, `metrics`, `logs`) beneath that shared temporary…

Product

nuget: OpenTelemetry.Exporter.OpenTelemetryProtocol

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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