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firefox-devtools-mcp MCP Server Security Report

mozilla/firefox-devtools-mcp

Model Context Protocol server for Firefox DevTools - enables AI assistants to inspect and control Firefox browser through the Remote Debugging Protocol

Security Trust Score
Grade B · Moderate posture
Tier 1 · Public sourceHigh confidence · 98%latest vmain@a739850 Repository
Declared MCP capabilities
ResourcesPrompts

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The short answer

Is firefox-devtools-mcp safe to use?
firefox-devtools-mcp scores 84/100 (grade B) on the Canopii Trust Index — good, minor gaps. It passes 15 of the 21 security controls that apply to it, with no confirmed security failures.
How reliable is the security score for firefox-devtools-mcp?
We could evaluate 98% of the controls that apply to firefox-devtools-mcp. Scores are deterministic — the same source always produces the same score — and a partially-scannable server cannot present a high one, because confidence caps the result. The scanner is open source, so this score can be reproduced independently.
How was firefox-devtools-mcp scored?
Its published source was scanned against a fixed catalog of weighted security controls covering code safety, committed secrets, dependency vulnerabilities, tool-description integrity, authentication and transport, and maintenance. A confirmed flaw caps the score outright regardless of what else passes. The full rubric is published.
Reputation552stars76forks4open issues3d agolast commit1yage

Security controlslatest scored version vmain@a739850

Each control is evaluated deterministically with evidence. The score is earned from passing controls; a failed guard caps it.

Model–MCP Runtime Guardrails

  • Warn
    Strict JSON Schema Enforcementschemas not strict

    Tool inputs are constrained (additionalProperties:false), so unexpected arguments can't be smuggled in.

    Fix: Set additionalProperties:false and require explicit parameters on every tool.

  • Pass
    Indirect Prompt Injection (IPI) Defensesguardno injection markers

    Tool/prompt/resource text is free of hidden instructions that could hijack the agent.

  • Pass
    Tool Definition Integrityguardtool definitions stable; no risky changes in version history

    Every consecutive version pair is diffed for new injection markers or destructive scope — a risky diff anywhere in history is a rug-pull (fail, durable); benign description drift warns.

  • Pass
    User-in-the-Loop / Approval Scopeguardno destructive tool scope

    No over-broad or destructive tools (arbitrary shell, bulk-delete) that warrant human approval.

Application Security Checks

  • Warn
    No command-injection sinksguard2 occurrences (build/test paths only)

    Untrusted tool input reaching a shell yields remote code execution.

    scripts/build-mcpb.mjs:50scripts/publish-moz-package.mjs:41

    Fix: Never pass tool arguments to a shell; use argv arrays with shell disabled.

  • Warn
    No path traversalguard5 occurrences

    Naive path checks let tools read/write outside intended directories (EscapeRoute-class).

    src/utils/js-validation.ts:22src/utils/js-validation.ts:23src/utils/js-validation.ts:24src/utils/js-validation.ts:25

    Fix: Resolve to a canonical path and verify containment; reject ../ and symlinks.

  • Warn
    No known-vulnerable dependencies9 of 139 runtime deps vulnerable; worst critical

    Runtime dependencies (parsed from the lockfile) are scanned against OSV.dev for published CVEs. Advisory: flagged dependencies lower the score but don't hard-cap it, since transitive reachability is unproven.

    @hono/[email protected] — GHSA-rmxm-3fg6-px4f@modelcontextprotocol/[email protected] — GHSA-22jm-h49p-29qw@modelcontextprotocol/[email protected] — GHSA-46jr-4wx8-v453@modelcontextprotocol/[email protected] — GHSA-6prh-2h8m-c8cw

    Fix: Upgrade the flagged dependencies past their fixed versions.

  • Warn
    Declares a licenseno recognized license

    A clear license is required for legal enterprise use.

    Fix: Add a recognized SPDX license (MIT, Apache-2.0, …).

  • Pass
    No dynamic code executionguardno sinks found

    eval()/exec()/Function() on tool-derived strings allows arbitrary code execution.

  • Pass
    No SSRF sinksguardno sinks found

    Fetching tool-supplied URLs can pivot into internal networks and metadata services.

  • Pass
    No unsafe deserializationguardno sinks found

    pickle/yaml.load/etc. on untrusted data can execute code.

  • Pass
    No committed secretsguardno secrets found

    Hardcoded keys/tokens in published source are live credentials an attacker can use.

  • Pass
    Credentials sourced from environmentreads credentials from environment

    Reading secrets from env/secret stores avoids hardcoding them.

  • Pass
    Dependencies pinned (lockfile)lockfile present

    A lockfile makes installs reproducible and resistant to silent dependency swaps.

  • Pass
    Actively maintainedrecent commits

    Unmaintained servers don't receive security fixes.

  • Pass
    Repository not archivedguardactive

    Archived repositories will never be patched.

  • Pass
    Has a security policySECURITY.md present

    A SECURITY.md gives a private path to report vulnerabilities.

  • Pass
    Adoption & popularityestablished adoption

    A small, capped nudge from stars/downloads — widely-used servers get more eyes on bugs. It can never offset a real security failure.

  • Not checked
    Signed releasesnot evaluated

    Signed releases let consumers verify artifacts weren't tampered with.

  • N/A
    No install/post-install scriptsguardno published package

    install hooks run arbitrary code on every consumer at install time.

  • N/A
    Package name not typosquattingguardno published package

    Names mimicking popular packages are a common malware delivery vector.

  • N/A
    Published with provenanceno published package

    Build provenance attests the artifact was built from the claimed source by CI.

  • N/A
    Established maintainerno published package

    Brand-new / single anonymous maintainers raise takeover and malware risk.

Transport & Trust Model

  • Pass
    Execution Sandboxingcontainerized

    A container/sandbox image limits blast radius; a server that runs natively has full host access.

  • Pass
    Network Exposureno bind-all detected

    Binding 0.0.0.0 or exposing debug inspectors widens the attack surface.

  • N/A
    Transport Encryption (TLS)guardno remote endpoints

    Plaintext HTTP exposes traffic and bearer tokens to interception.

  • N/A
    IAM / Authentication Scopingno remote endpoints

    OAuth 2.1 / Protected Resource Metadata gates who can invoke tools.

  • N/A
    Live Endpoint Reachablenot dynamically scanned

    A dynamic scan connected to the declared remote endpoint and it responded — verified live, not a dead URL.

  • N/A
    Authentication Enforced (live)not dynamically scanned

    If the server declares auth is required, it must actually reject anonymous clients. Serving tools to unauthenticated callers is a real exposure.

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Versions

VersionScoreStatus
vmain@a739850latest84Bscored
vmain@025b37e84Bscored
vmain@0eaaa9f84Bscored
vmain@dd67f9f84Bscored
vmain@eaf200882Bscored
vmain@58a4e7f82Bscored
vmain@dc2cb9b84Bscored
vmain@f3f964e84Bscored
vmain@ab64abc84Bscored
vmain@2eb2cb284Bscored
vmain@eba66ed84Bscored
vmain@dff834a84Bscored
vmain@521eb2b85Bscored
vmain@e9e2efb85Bscored
vmain@5c6988885Bscored
vmain@1aaeb2985Bscored
vmain@c5b79a985Bscored
vmain@bdb377a85Bscored
vmain@8f6e93085Bscored
vmain@af2661782Bscored
vmain@0038ae282Bscored
vmain@67d972382Bscored
vmain@8183cc785Bscored
vmain@a70e6dd85Bscored
vmain@d1b688285Bscored
vmain@be4f24984Bscored
vmain@538a07b82Bscored
vmain@78356d585Bscored
vmain@689389385Bscored
vmain@634a75685Bscored
vmain@4e3b26485Bscored
vmain@e04a95585Bscored
vmain@01f2d1c85Bscored
vmain@009187d85Bscored
vmain@8ba033385Bscored
vmain@49f864485Bscored
vmain@9934d4c85Bscored
vmain@d79e34685Bscored
vmain@481dc0185Bscored
vmain@2b84b9784Bscored

Wondering how this compares? The MCP Security Index tracks grade distribution, committed secrets, and missing authentication across the whole ecosystem, refreshed monthly.