OpenTelemetry Go up to 0.20.x gRPC TLS Configuration otlploggrpc newGRPCDialOptions certificate validation

Summaryinfo

A vulnerability was found in OpenTelemetry Go up to 0.20.x and classified as problematic. This affects the function newGRPCDialOptions of the file exporters/otlp/otlplog/otlploggrpc of the component gRPC TLS Configuration. Executing a manipulation can lead to certificate validation. The identification of this vulnerability is CVE-2026-81871. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in OpenTelemetry Go up to 0.20.x. This vulnerability affects the function newGRPCDialOptions of the file exporters/otlp/otlplog/otlploggrpc of the component gRPC TLS Configuration. The manipulation with an unknown input leads to a certificate validation vulnerability. The CWE definition for the vulnerability is CWE-295. The product does not validate, or incorrectly validates, a certificate. As an impact it is known to affect integrity. CVE summarizes:

OpenTelemetry-Go is the Go implementation of OpenTelemetry. Prior to version 0.21.0, the exporters/otlp/otlplog/otlploggrpc package loads OTEL_EXPORTER_OTLP_LOGS_CERTIFICATE, OTEL_EXPORTER_OTLP_CERTIFICATE, and related client certificate environment variables through loadEnvTLS into cfg.tlsCfg, but newGRPCDialOptions does not apply cfg.tlsCfg when creating gRPC transport credentials. The environment-only TLS path instead uses credentials.NewTLS with system roots and no configured client certificate, bypassing intended private CA pinning and mutual TLS unless the application also supplies WithTLSCredentials. A network attacker able to intercept or spoof the collector connection with a system-trusted certificate can read or alter log telemetry. This issue is fixed in version 0.21.0.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-81871 since 08/27/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1587.003.

Upgrading to version 0.21.0 eliminates this vulnerability.

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Productinfo

Vendor

• OpenTelemetry

Name

• Go

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20

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