Vulnerability in github.com/googleapis/mcp-toolbox (CVE-2026-9739)
Summary
Vulnerability in github.com/googleapis/mcp-toolbox (CVE-2026-9739). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 1.2.0 or later.
Original description
The description as published by the source.
Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented allowed-origins and allowed-hosts flags to align with MCP security guidelines. However, the hardcoded Access-Control-Allow-Origin: * header in the SSE initialization handler was inadvertently retained. This vulnerability specifically impacts users connecting via Toolbox using SSE under specification v2024-11-05.
Source: NIST National Vulnerability Database 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-2026-9739 has been found in github.com/googleapis/mcp-toolbox.
Risk of unauthorized operations or information disclosure.
What to do: upgrade github.com/googleapis/mcp-toolbox to 1.2.0 or later.
If unsure, ask your IT team or search "github.com/googleapis/mcp-toolbox CVE-2026-9739" on the vendor's site.
CVE-2026-9739 (github.com/googleapis/mcp-toolbox) — CWE-942
Patched: 1.2.0 — 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.
A vulnerability (CWE-942) exists in github.com/googleapis/mcp-toolbox.
Check the vendor advisory for the affected versions of github.com/googleapis/mcp-toolbox.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 1.2.0.
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 1.2.0ステージング環境で 1.2.0 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
- package github.com
- web github.com
- web github.com
- web github.com