CVE-2026-81871Public exploitNetwork attack vector

Telemetry interception and alteration via ignored TLS configuration

Published Sep 16, 2026 · Updated Sep 17, 2026

Improper certificate validation in OpenTelemetry-Go before 0.21.0 allows man-in-the-middle attackers to read or alter log telemetry. The OTLP log gRPC exporter loads environment-provided CA and client certificates into cfg.tlsCfg, but newGRPCDialOptions ignores that object and creates credentials with system roots and no client certificate. Exploitation requires interception or spoofing of the collector connection with a system-trusted certificate and environment-only TLS configuration without WithTLSCredentials.

CVSS severity6.3
Medium
EPSS probability0.20%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in OpenTelemetry-Go before 0.21.0 allows man-in-the-middle attackers to read or alter log telemetry. The OTLP log gRPC exporter loads environment-provided CA and client certificates into cfg.tlsCfg, but newGRPCDialOptions ignores that object and creates credentials with system roots and no client certificate. Exploitation requires interception or spoofing of the collector connection with a system-trusted certificate and environment-only TLS configuration without WithTLSCredentials.

The record

CVE
CVE-2026-81871
Published
Sep 16, 2026
Updated
Sep 17, 2026
Vendor
OpenTelemetry
Product
OpenTelemetry-Go
Classifications
CWE-295, CWE-923, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.21.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenTelemetry · OpenTelemetry-Goversion=< 0.21.0

Published CVSS scores

6.3GitHub CNACVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-295Improper Certificate Validation
CWE-923Improper Restriction of Communication Channel to Intended Endpoints
T1557Adversary-in-the-Middle

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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