Vulnerability · Published Sep 16, 2026 · Assigned by GitHub_M
CVE-2026-81871OpenTelemetry-Go: Log gRPC exporter ignores env TLS certs, bypassing mTLS/pinning
Medium 6.3
In plain English
A medium-severity improper certificate validation in opentelemetry-go from open-telemetry. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | golang-opentelemetry-otel | no fix listed | DEBIAN-CVE-2026-81871 |
| Debian:14 | golang-opentelemetry-otel | no fix listed | DEBIAN-CVE-2026-81871 |
| Go | go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc | 0.21.0 | GHSA-w34q-cm8f-9c5x |
| Go | go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc | 0.21.0 | GO-2026-6508 |
| Ubuntu:22.04:LTS | golang-opentelemetry-otel | no fix listed | UBUNTU-CVE-2026-81871 |
| Ubuntu:24.04:LTS | golang-opentelemetry-otel | no fix listed | UBUNTU-CVE-2026-81871 |
| Ubuntu:26.04:LTS | golang-opentelemetry-otel | no fix listed | UBUNTU-CVE-2026-81871 |
| Ubuntu:26.10 | golang-opentelemetry-otel | no fix listed | UBUNTU-CVE-2026-81871 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| open-telemetry | opentelemetry-go | < 0.21.0 |
Weakness: CWE-295, CWE-923 · 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
References
- https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-w34q-cm8f-9c5x x_refsource_CONFIRM
- https://github.com/open-telemetry/opentelemetry-go/commit/c65d435b43e5e6b82310e6b18dd4cdcb8ac63a0c x_refsource_MISC
- https://github.com/open-telemetry/opentelemetry-go/releases/tag/exporters/otlp/otlplog/otlploggrpc/v0.21.0 x_refsource_MISC