CVE-2026-105216 in go-micro
Summary
by MITRE • 10/04/2026
go-micro before 6.0.0 contains an improper certificate validation vulnerability that allows network attackers to impersonate services because the shared TLS helper sets InsecureSkipVerify to true by default. Man-in-the-middle attackers can present any certificate to intercept or modify gRPC transport, HTTP and RabbitMQ broker, and Consul or etcd registry traffic, including authentication tokens and credentials.
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Analysis
by VulDB Data Team • 10/04/2026
The vulnerability identified in go-micro versions prior to 6.0.0 represents a critical failure in Transport Layer Security implementation within the framework's core networking components. The root cause lies in the default configuration of the shared TLS helper function, which explicitly sets the InsecureSkipVerify flag to true. This setting instructs the underlying Go standard library crypto/tls package to bypass all certificate validation procedures during the handshake process. Consequently, when clients or servers establish connections using this helper, they do not verify that the remote peer's X.509 certificate is signed by a trusted Certificate Authority, nor do they validate that the certificate matches the expected hostname via Subject Alternative Name checks. This design choice effectively disables mutual authentication and integrity verification for all services relying on this default configuration, creating a systemic weakness across the entire microservices architecture built upon go-micro.
From an operational perspective, this flaw enables severe Man-in-the-Middle attacks against any communication channel managed by the framework. Attackers positioned within the network path can intercept traffic between gRPC clients and servers, HTTP-based service calls, or messages exchanged via RabbitMQ brokers and Consul or etcd registries. By presenting a self-signed certificate that matches no specific hostname requirements due to the skipped verification, an attacker can successfully establish encrypted connections with both parties without detection. This allows for the complete interception of sensitive data transmitted over these channels. The impact is particularly acute regarding authentication tokens, session cookies, and service credentials which are often passed in headers or message payloads during initial connection setup and subsequent interactions.
The exploitation of this vulnerability facilitates unauthorized access to backend services and databases connected through the registry components like Consul or etcd. An attacker can impersonate a legitimate microservice by presenting their own certificate, tricking other services into sending requests containing sensitive operational data or administrative commands. In environments where service discovery relies on these registries, an attacker could also register malicious endpoints under valid-looking names, further complicating detection efforts. The ability to modify traffic means that not only can data be stolen in transit, but it can also be altered before reaching its destination, potentially leading to logic flaws or injection attacks within the application layer if input validation is insufficient on the receiving end.
This vulnerability aligns with CWE-295 Improper Certificate Validation and falls under MITRE ATT&CK technique T1078 Valid Accounts when used for impersonation, as well as T1043 Shared Transport Channel due to the exploitation of a shared communication pathway. The severity is heightened by the fact that it affects default configurations, meaning developers may remain unaware of the risk unless they explicitly audit their TLS settings or upgrade to version 6.0.0 where this behavior has been corrected. To mitigate this issue, organizations must immediately update go-micro to version 6.0.0 or later. For environments unable to upgrade instantly, a temporary workaround involves ensuring that all service configurations explicitly disable the use of the shared TLS helper and instead implement custom TLS configuration logic with InsecureSkipVerify set to false. Additionally, enforcing strict certificate pinning for critical internal services can provide an additional layer of defense against impersonation attacks until the framework update is fully deployed across the infrastructure.