CVE-2026-11720: Github.com/googleapis/mcp toolbox MCP Toolbox HTTP Tool Path Vulnerability
CRITICALCVE-2026-11720 is a CRITICAL (CVSS 9.1) mcp toolbox http tool path vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Github.com/googleapis/mcp toolbox libraries in the Go ecosystem. The issue involves mcp toolbox http tool path parameters allow traversal to unintended endpoints. Remediation is available by upgrading affected packages to version 1.3.0.
CVE-2026-11720 at a Glance
Security Impact
CVSS: 9.1
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N).
How to Fix CVE-2026-11720
To remediate this vulnerability, upgrade all affected Github.com/googleapis/mcp toolbox dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade github.com/googleapis/mcp-toolbox to 1.3.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for github.com/googleapis/mcp-toolboxHow to Check if You Are Affected
To determine whether your application is affected by CVE-2026-11720, inspect your project dependencies for Github.com/googleapis/mcp toolbox:
inspect dependencies for github.com/googleapis/mcp-toolboxAnalyze the terminal output to locate any version of Github.com/googleapis/mcp toolbox in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.3.0), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. In Github.com/googleapis/mcp toolbox, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-11720 Affected Github.com/googleapis/mcp toolbox Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
github.com/googleapis/mcp-toolbox
|
Go |
< 1.3.0
|
1.3.0
|
References
Frequently Asked Questions
What is CVE-2026-11720?
Which Github.com/googleapis/mcp toolbox versions are affected?
What version fixes CVE-2026-11720?
Is github.com/googleapis/mcp-toolbox affected?
What is the CVSS score of CVE-2026-11720?
What CWE is associated with CVE-2026-11720?
How can I check Go dependencies for CVE-2026-11720?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-vwxw-jrg6-9jxv",
"modified" : "2026-09-04T19:21:10Z",
"published" : "2026-06-29T18:31:55Z",
"aliases" : [ "CVE-2026-11720" ],
"summary" : "MCP Toolbox HTTP tool path parameters allow traversal to unintended endpoints",
"details" : "A path traversal vulnerability exists in the HTTP tool URL builder of googleapis/mcp-toolbox.\n\nWhen 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).",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
}, {
"type" : "CVSS_V4",
"score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/googleapis/mcp-toolbox"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "1.3.0"
} ]
} ]
} ],
"references" : [ {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-11720"
}, {
"type" : "WEB",
"url" : "https://github.com/googleapis/mcp-toolbox/pull/3218"
}, {
"type" : "WEB",
"url" : "https://github.com/googleapis/mcp-toolbox/commit/80a66021205e032a424fff87b3dc6d92da58aa77"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/googleapis/mcp-toolbox"
}, {
"type" : "WEB",
"url" : "https://github.com/googleapis/mcp-toolbox/releases/tag/v1.3.0"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-22" ],
"severity" : "CRITICAL",
"github_reviewed" : true,
"github_reviewed_at" : "2026-09-04T19:21:10Z",
"nvd_published_at" : "2026-06-29T18:16:36Z"
}
}