Summary
A path traversal vulnerability in the NetLicensing MCP Server allows an authenticated MCP client to manipulate a product identifier so a request reaches a token endpoint instead of the intended product resource. The resulting response can expose plaintext licensing tokens, including administrative tokens that may enable broad access to the NetLicensing account.
A path traversal vulnerability in the NetLicensing MCP Server allows an authenticated MCP client to manipulate a product identifier so a request reaches a token endpoint instead of the intended product resource. The resulting response can expose plaintext licensing tokens, including administrative tokens that may enable broad access to the NetLicensing account.
Affected context
The issue affects NetLicensing MCP Server deployments that use versions before 0.1.8 and expose the product retrieval tool to authenticated MCP clients. Risk arises when caller-controlled product identifiers are inserted into REST paths without validating path boundaries or enforcing that requests remain within the intended resource namespace. Response handling can also matter when token data bypasses the redaction logic intended for token-specific responses.
The issue affects NetLicensing MCP Server deployments that use versions before 0.1.8 and expose the product retrieval tool to authenticated MCP clients. Risk arises when caller-controlled product identifiers are inserted into REST paths without validating path boundaries or enforcing that requests remain within the intended resource namespace. Response handling can also matter when token data bypasses the redaction logic intended for token-specific responses.
Exploit preconditions
- Attack surface: The authenticated MCP interface and its product retrieval tool
- Required access: An authenticated MCP client with a non-administrative API key
- Trigger point: Processing a caller-controlled product number as part of a REST resource path
- Why exploitation is possible: The path component is not constrained to a single valid segment, allowing normalization to redirect the request to a token endpoint where a less restrictive response serializer is used
- Escalation condition: A disclosed administrative token could provide substantially broader read, write, and delete capabilities
- Attack surface: The authenticated MCP interface and its product retrieval tool
- Required access: An authenticated MCP client with a non-administrative API key
- Trigger point: Processing a caller-controlled product number as part of a REST resource path
- Why exploitation is possible: The path component is not constrained to a single valid segment, allowing normalization to redirect the request to a token endpoint where a less restrictive response serializer is used
- Escalation condition: A disclosed administrative token could provide substantially broader read, write, and delete capabilities
Why this happens
The underlying bug is improper neutralization and validation of user-controlled path components, mapping to CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'). The application interpolates a caller-controlled identifier into a REST path without verifying that it represents one permitted resource segment. Path normalization can therefore change the addressed endpoint, while endpoint-specific redaction is applied inconsistently and may expose sensitive token fields.
The underlying bug is improper neutralization and validation of user-controlled path components, mapping to CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'). The application interpolates a caller-controlled identifier into a REST path without verifying that it represents one permitted resource segment. Path normalization can therefore change the addressed endpoint, while endpoint-specific redaction is applied inconsistently and may expose sensitive token fields.
Potential impact
- Plaintext API key or token values may be disclosed
- Shop URLs and other sensitive account metadata could be exposed
- A recovered administrative token could enable unauthorized account changes
- Licensing data may be read, modified, or deleted
- Downstream agentic applications could be abused as a credential-disclosure channel
- Compromised credentials could support further attacks against integrated services
- Plaintext API key or token values may be disclosed
- Shop URLs and other sensitive account metadata could be exposed
- A recovered administrative token could enable unauthorized account changes
- Licensing data may be read, modified, or deleted
- Downstream agentic applications could be abused as a credential-disclosure channel
- Compromised credentials could support further attacks against integrated services
General mitigation guidance
Mitigation generally centers on treating resource identifiers as data rather than path syntax and maintaining consistent secret-handling controls.
Common defensive patterns include:
- Validate product identifiers against a strict allowlist of permitted characters and exactly one path segment
- Encode path parameters with a URI-aware mechanism instead of concatenating raw strings
- Reject traversal markers, encoded separators, normalization changes, and unexpected path components
- Bind each MCP tool to an explicit allowed endpoint and resource type
- Apply redaction uniformly to all responses that may contain credentials
- Return only the minimum fields required by the tool
- Use least-privilege API keys and separate administrative credentials from routine integrations
- Rotate credentials that may have been exposed and review access logs for anomalous endpoint requests
Mitigation generally centers on treating resource identifiers as data rather than path syntax and maintaining consistent secret-handling controls.
Common defensive patterns include:
- Validate product identifiers against a strict allowlist of permitted characters and exactly one path segment
- Encode path parameters with a URI-aware mechanism instead of concatenating raw strings
- Reject traversal markers, encoded separators, normalization changes, and unexpected path components
- Bind each MCP tool to an explicit allowed endpoint and resource type
- Apply redaction uniformly to all responses that may contain credentials
- Return only the minimum fields required by the tool
- Use least-privilege API keys and separate administrative credentials from routine integrations
- Rotate credentials that may have been exposed and review access logs for anomalous endpoint requests
How teams detect issues like this
Detection can combine static analysis, review practices, runtime telemetry, and policy enforcement.
Useful approaches include:
- Search for string interpolation or concatenation of caller-controlled values into URL paths
- Flag REST clients that accept raw path fragments without segment validation or encoding
- Review whether endpoint-specific serializers can be selected by changing a user-controlled path
- Add tests for traversal markers, encoded separators, dot segments, and normalization changes
- Monitor requests for unexpected token-endpoint access through product-oriented tools
- Alert when non-administrative clients receive token-shaped fields or when administrative tokens are used unusually
- Enforce automated review rules that prohibit unvalidated path construction and plaintext secret serialization
Detection can combine static analysis, review practices, runtime telemetry, and policy enforcement.
Useful approaches include:
- Search for string interpolation or concatenation of caller-controlled values into URL paths
- Flag REST clients that accept raw path fragments without segment validation or encoding
- Review whether endpoint-specific serializers can be selected by changing a user-controlled path
- Add tests for traversal markers, encoded separators, dot segments, and normalization changes
- Monitor requests for unexpected token-endpoint access through product-oriented tools
- Alert when non-administrative clients receive token-shaped fields or when administrative tokens are used unusually
- Enforce automated review rules that prohibit unvalidated path construction and plaintext secret serialization
