A path traversal vulnerability exists in the HTTP tool URL builder of googleapis/mcp-toolbox.
When constructing downstream API requests, the URL builder substitutes user-controlled pathParams into the configured tool path and parses the resulting string as a relative URL. While it checks that the input does not alter the scheme, host, or user info, it relies on ResolveReference for the final URL resolution. Because dot segments (../) are normalized during this resolution step, an attacker can supply path parameters containing directory traversal sequences to escape the operator-configured path scope. This allows the client to coerce the toolbox into making requests to unintended endpoints on the same target host while forwarding the toolbox's configured credentials (e.g., bypassing a restricted path like /api/v1/users/{{.id}} to reach /admin/secrets).
When constructing downstream API requests, the URL builder substitutes user-controlled pathParams into the configured tool path and parses the resulting string as a relative URL. While it checks that the input does not alter the scheme, host, or user info, it relies on ResolveReference for the final URL resolution. Because dot segments (../) are normalized during this resolution step, an attacker can supply path parameters containing directory traversal sequences to escape the operator-configured path scope. This allows the client to coerce the toolbox into making requests to unintended endpoints on the same target host while forwarding the toolbox's configured credentials (e.g., bypassing a restricted path like /api/v1/users/{{.id}} to reach /admin/secrets).
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References
| Link | Providers |
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| https://github.com/googleapis/mcp-toolbox/pull/3218 |
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History
Mon, 29 Jun 2026 19:30:00 +0000
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ssvc
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Mon, 29 Jun 2026 18:15:00 +0000
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| Description | A path traversal vulnerability exists in the HTTP tool URL builder of googleapis/mcp-toolbox. When constructing downstream API requests, the URL builder substitutes user-controlled pathParams into the configured tool path and parses the resulting string as a relative URL. While it checks that the input does not alter the scheme, host, or user info, it relies on ResolveReference for the final URL resolution. Because dot segments (../) are normalized during this resolution step, an attacker can supply path parameters containing directory traversal sequences to escape the operator-configured path scope. This allows the client to coerce the toolbox into making requests to unintended endpoints on the same target host while forwarding the toolbox's configured credentials (e.g., bypassing a restricted path like /api/v1/users/{{.id}} to reach /admin/secrets). | |
| Title | Path Traversal in googleapis/mcp-toolbox HTTP Tool URL Builder | |
| Weaknesses | CWE-22 | |
| References |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: Google
Published:
Updated: 2026-06-29T18:26:17.242Z
Reserved: 2026-06-09T00:57:55.333Z
Link: CVE-2026-11720
Updated: 2026-06-29T18:25:41.698Z
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Weaknesses