# CVE-2026-14541: Authentication Bypass and Audience Confusion in MCP Toolbox OAuth Provider

> Attackers can bypass authentication in Google MCP Toolbox by using unrelated OAuth tokens when audience validation is skipped due to missing configuration.

- **Severity:** High 8.0 (`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/E:U`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 31 Jul 2026
- **Updated:** 31 Jul 2026
- **Also known as:** GHSA-656w-qf75-c5gf

## What is CVE-2026-14541?

CVE-2026-14541 is a high-severity authentication bypass vulnerability in Google mcp-toolbox, published on 31 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An authentication bypass and audience confusion vulnerability exists in the Google OAuth provider component of Google mcp-toolbox version 1.4.0. When a Google authService is initialized with mcpEnabled: true but lacks an explicitly defined audience or clientId, the ValidateMCPAuth pipeline for opaque tokens skips audience validation entirely. As a result, the toolbox will accept any valid Google OAuth access token—even those minted for unrelated ecosystem applications—granting unauthorized clients access to protected tools and data backends.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-14541?

It affects 1 product.


Products: Google Mcp Toolbox for Databases.

## How do I fix CVE-2026-14541?

No fix has been published for CVE-2026-14541 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-14541 being exploited?

There is no known exploitation of CVE-2026-14541 in the wild and no public exploit code.

## Other vulnerabilities in Google mcp-toolbox

- [CVE-2026-11720](https://insights.sbomify.com/CVE-2026-11720/): Path Traversal in googleapis/mcp-toolbox HTTP Tool URL Builder (critical 9.3)
- [CVE-2026-11717](https://insights.sbomify.com/CVE-2026-11717/): googleapis/mcp-toolbox: authentication bypass vulnerability in the generic opaque token validation path (validateOpaqueToken) (critical 9.3)
- [CVE-2026-11718](https://insights.sbomify.com/CVE-2026-11718/): googleapis/mcp-toolbox: authentication bypass vulnerability in the generic opaque token validation path (validateOpaqueToken) (critical 9.3)
- [CVE-2026-15829](https://insights.sbomify.com/CVE-2026-15829/): SQL Injection and Security Boundary Bypass in googleapis/mcp-toolbox (high 8.6)
- [CVE-2026-11719](https://insights.sbomify.com/CVE-2026-11719/): MCP Toolbox for Databases: authenticated authorization bypass (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-14541 and fix it if it is affected.

What it is: CVE-2026-14541 is a high-severity authentication bypass vulnerability in Google mcp-toolbox, published on 31 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-14541 in the wild and no public exploit code.

Affected product: Google mcp-toolbox. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-14541/ (Markdown: https://insights.sbomify.com/CVE-2026-14541/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-14541
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-14541
- OSV: https://osv.dev/vulnerability/CVE-2026-14541

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-14541/
Summaries are generated and may contain mistakes; the official description above is the record.