Authentication Bypass in github.com/googleapis/mcp-toolbox (CVE-2026-11717)
Summary
Authentication bypass in github.com/googleapis/mcp-toolbox (CVE-2026-11717). Confidential information can be exposed externally. Mitigation: upgrade to 1.4.0 or later.
Original description
The description as published by the source.
An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox.
When verifying an unparsed opaque token via an OAuth 2.0 introspection endpoint (RFC 7662), the toolbox decodes the response into an introspectResp struct where the Active field is declared as a pointer to a boolean (*bool). The code only explicitly rejects a token if the response contains a populated active field set to false (if introspectResp.Active != nil && !*introspectResp.Active). If an introspection endpoint responds with a payload that completely omits the mandatory active key, the internal variable remains nil, causing the conditional check to short-circuit. As a result, Toolbox accepts authorization tokens missing the "active" field, granting access to protected tools and underlying data sources.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-11717 has been found in github.com/googleapis/mcp-toolbox.
Confidential information can be exposed externally. CVSS score: 9.1/10.
What to do: upgrade github.com/googleapis/mcp-toolbox to 1.4.0 or later.
If unsure, ask your IT team or search "github.com/googleapis/mcp-toolbox CVE-2026-11717" on the vendor's site.
CVE-2026-11717 (github.com/googleapis/mcp-toolbox) — CWE-287 / CVSS v3 9.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.4.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Authentication bypass (CWE-287) exists in github.com/googleapis/mcp-toolbox.
Check the vendor advisory for the affected versions of github.com/googleapis/mcp-toolbox.
Severity: Critical (CVSS 9.1/10). Confidential information can be exposed externally.
Update to 1.4.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/googleapis/mcp-toolbox' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'github.com/googleapis/mcp-toolbox' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/googleapis/mcp-toolboxを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade github.com/googleapis/mcp-toolbox to 1.4.0ステージング環境で 1.4.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- advisory github.com
- advisory github.com
- package github.com
- patch github.com