{"id":"CVE-2026-81871","state":"PUBLISHED","title":"OpenTelemetry-Go: Log gRPC exporter ignores env TLS certs, bypassing mTLS/pinning","description":"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.","publishedAt":"2026-09-16T20:43:40.119Z","updatedAt":"2026-09-17T19:24:00.081Z","severity":{"score":6.3,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["open-telemetry opentelemetry-go"],"affected":[{"vendor":"open-telemetry","product":"opentelemetry-go","versions":[{"version":"< 0.21.0","status":"affected"}]}],"references":["https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-w34q-cm8f-9c5x","https://github.com/open-telemetry/opentelemetry-go/commit/c65d435b43e5e6b82310e6b18dd4cdcb8ac63a0c","https://github.com/open-telemetry/opentelemetry-go/releases/tag/exporters/otlp/otlplog/otlploggrpc/v0.21.0"],"weaknesses":["CWE-295","CWE-923"],"ingestedAt":"2026-10-29T20:13:15.269Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/81xxx/CVE-2026-81871.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-81871","state":"PUBLISHED","datePublished":"2026-09-16T20:43:40.119Z","dateUpdated":"2026-09-17T19:24:00.081Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-27T17:48:42.120Z"},"containers":{"cna":{"title":"OpenTelemetry-Go: Log gRPC exporter ignores env TLS certs, bypassing mTLS/pinning","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"open-telemetry","product":"opentelemetry-go","versions":[{"version":"< 0.21.0","status":"affected"}]}],"references":[{"url":"https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-w34q-cm8f-9c5x","name":"https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-w34q-cm8f-9c5x","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/open-telemetry/opentelemetry-go/commit/c65d435b43e5e6b82310e6b18dd4cdcb8ac63a0c","name":"https://github.com/open-telemetry/opentelemetry-go/commit/c65d435b43e5e6b82310e6b18dd4cdcb8ac63a0c","tags":["x_refsource_MISC"]},{"url":"https://github.com/open-telemetry/opentelemetry-go/releases/tag/exporters/otlp/otlplog/otlploggrpc/v0.21.0","name":"https://github.com/open-telemetry/opentelemetry-go/releases/tag/exporters/otlp/otlplog/otlploggrpc/v0.21.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":6.3,"baseSeverity":"MEDIUM","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-295","lang":"en","description":"CWE-295: Improper Certificate Validation","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-923","lang":"en","description":"CWE-923: Improper Restriction of Communication Channel to Intended Endpoints","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-16T20:43:40.119Z"},"source":{"advisory":"GHSA-w34q-cm8f-9c5x","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-17T17:10:34.419383Z","id":"CVE-2026-81871","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-17T19:24:00.081Z"}}]}}}