What’s Vulnerable › Vulnerabilities

CVE-2026-42191: OpenTelemetry.Exporter.OpenTelemetryProtocol: Disk retry default temp path enables local blob injection for OTLP Exporter

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-12 · updated 2026-10-26
• Weakness: CWE-379

Description

OpenTelemetry.Exporter.OpenTelemetryProtocol is the OTLP (OpenTelemetry Protocol) exporter implementation. From 1.8.0 to 1.15.2, 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 root path. On multi-user systems where the temporary directory is accessible to other local accounts, this allows an attacker to write crafted *.blob files, read *.blob files written by the application between export failures, or deposit numerous or oversized blob files, degrading retry-loop performance or consuming disk space. This vulnerability is fixed in 1.15.3.

Affected products

• open-telemetry OpenTelemetry.Exporter.OpenTelemetryProtocol: from 1.8.0 before 1.15.3 — fixed in 1.15.3

How to fix

Upgrade to a fixed version: open-telemetry OpenTelemetry.Exporter.OpenTelemetryProtocol 1.15.3. Check the vendor advisory for mitigations.

References

• https://github.com/open-telemetry/opentelemetry-dotnet/pull/7106
• https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-4625-4j76-fww9

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