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Rule Reference

SEC303lintai-ai-securitystablejsonwarn

MCP config: credential env passthrough

MCP configuration passes through credential environment variables

Provider
lintai-ai-security
Surface
json
Scope
per_file
Tier
stable
Severity
warn
Confidence
high
Detection
structural
Remediation
message_only

Activation Model

Preset Membership

This rule is part of the builtin activation graph through these preset memberships.

basemembership
mcpmembership

Lifecycle

Stable Lifecycle Contract

State

stable_gated

Graduation rationale

Matches explicit credential env passthrough by key inside configuration env maps.

Deterministic signal basis

JsonSignals env-map key observation for credential passthrough keys.

Malicious corpus
mcp-credential-env-passthrough
Benign corpus
mcp-safe-basic
structured evidence required remediation reviewed
Canonical note

Structural stable rule intended as a high-precision check with deterministic evidence.

Nearby Signals

Related Rules

SEC301MCP config: shell trampolineMCP configuration shells out through sh -c or bash -cjsonstable
SEC302Config: insecure HTTP endpointConfiguration contains an insecure http:// endpointjsonstable
SEC304Config: TLS verification disabledConfiguration disables TLS or certificate verificationjsonstable
SEC305Config: hardcoded auth materialConfiguration embeds static authentication material in a connection or auth valuejsonstable
SEC309Config: literal secrets in configConfiguration commits literal secret material in env, auth, or header valuesjsonstable
SEC310Config: metadata or private-network hostConfiguration endpoint targets a metadata or private-network host literaljsonstable

Why It Matters ​

Forwarding credential environment variables through committed MCP config broadens where secrets flow and makes it easier for downstream tools to inherit credentials they did not strictly need.

What Triggers ​

SEC303 applies to configuration env maps and triggers when a credential-shaped key forwards its value from the ambient environment.

Examples that trigger:

json
{"env":{"OPENAI_API_KEY":"${OPENAI_API_KEY}"}}
{"servers":{"demo":{"env":{"OPENAI_API_KEY":"${OPENAI_API_KEY}"}}}}

Example that stays clean:

json
{"env":{"WORKSPACE_ROOT":"${HOME}"}}

False Positives ​

The rule is scoped to credential-shaped env keys. It is not a generic env-reference detector, and it deliberately avoids duplicating the more general preview rule for non-credential sensitive env forwarding.

Remediation ​

Remove credential env passthrough from the committed config and configure the secret only inside the target service or runtime boundary that actually needs it.