CVE-2026-42191

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.

CVSS 3.1

7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

0.1% chance of exploitation in the next 30 days; higher than 1% of CVEs (scores of 2026-10-26)

CWE

CWE-379

Published

2026-05-12

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• opentelemetry:opentelemetry.exporter.opentelemetryprotocol

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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