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CVE-2026-81871— OpenTelemetry-Go: Log gRPC exporter ignores env TLS certs, bypassing mTLS/pinning

Quick assessment

Affected
open-telemetry opentelemetry-go
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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

CVSS 6.3 · Medium

Possible ATT&CK Techniques 1 AI

T1131
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I. Basic Information for CVE-2026-81871

Vulnerability Information
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Vulnerability Title
OpenTelemetry-Go: Log gRPC exporter ignores env TLS certs, bypassing mTLS/pinning
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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: CVE Program / CVE List V5
Vulnerability Type
证书验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
open-telemetry opentelemetry-go < 0.21.0 -

II. Public POCs for CVE-2026-81871

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III. Intelligence Information for CVE-2026-81871

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Patches & Fixes for CVE-2026-81871 (1)

Other References for CVE-2026-81871 (2)

Same Patch Batch · open-telemetry · 2026-09-16 · 4 CVEs total

CVE-2026-81872 6.3 MEDIUM OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full
CVE-2026-81869 5.1 MEDIUM OpenTelemetry-Go: UTF-8 replacement rune bypasses attribute length truncation
CVE-2026-81870 2.0 LOW OpenTelemetry-Go: Exporter config logging may leak endpoint URLs in info logs

IV. Related Vulnerabilities

Same product: opentelemetry-go
Same vendor: open-telemetry
Same weakness: CWE-295

V. Comments for CVE-2026-81871

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