Build123d MCP Server
build123d-mcp
PyPI
v0.3.84
Published by pzfreo — no publish provenance, so origin is unverified, but the source is public: the repository link below is self-declared yet readable, so you can inspect the code before adopting it.
MCP server wrapping build123d for interactive 3D CAD
The grade answers one question — how safe is this server for you to adopt — so it is computed in two auditable stages. Nothing below is an opinion or an LLM's guess; every line is a real term the deterministic engine applied, and the same input always yields the same number.
1. Threat score — 100 − 6.3 = 94. What the published surface and source actually contain:
| Points | What was found | Category |
|---|---|---|
| −6.3 | Unsafe deserialization MTC-SRC-007 | permissions |
2. Client adoption risk — 94 − 7 = 87. Three small, subtract-only factors that reflect your risk in adopting it — a clean scan proves less on a powerful, unverified or barely-inspectable package, so the grade says so plainly:
| Points | Adoption-risk factor |
|---|---|
| −6 | capability blast radius (high) — client exposure if the model is manipulated |
| −1 | publisher verification (public source) — no provenance, but the source is public and inspectable |
Capability observations and info notes are shown under Findings but never scored.
Open any row's finding below for the file, line and evidence behind a deduction.
Findings 13
high Dynamic code execution in server code (src/build123d_mcp/tools/library.py)MTC-SRC-001
In the server's implementation (`src/build123d_mcp/tools/library.py:160`): Evaluating strings as code is the most direct RCE primitive; if any tool input reaches it, the server executes attacker-chosen code. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: tricted_builtins()} exec(compile(source, entry["path"], "exec"), namespace) # noqa: S102 if "make" not in name
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/tools/library.py
high Dynamic code execution in server code (src/build123d_mcp/tools/resolve.py)MTC-SRC-001
In the server's implementation (`src/build123d_mcp/tools/resolve.py:234`): Evaluating strings as code is the most direct RCE primitive; if any tool input reaches it, the server executes attacker-chosen code. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: try: result = eval(expression, namespace) # noqa: S307 except Exception as exc: return json.dumps
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/tools/resolve.py
high Shell/command execution in server code (src/build123d_mcp/_design_audit_subprocess.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/_design_audit_subprocess.py:13`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: parent bound it with ``subprocess.run(timeout=)`` and kill this disposable child on overrun, without ever SIGKILLing th
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/_design_audit_subprocess.py
high Shell/command execution in server code (src/build123d_mcp/_shape_compare_subprocess.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/_shape_compare_subprocess.py:7`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: nds this process with ``subprocess.run(timeout=...)`` so the worker session survives a large or pathological part. Nois
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/_shape_compare_subprocess.py
high Shell/command execution in server code (src/build123d_mcp/_shape_op_subprocess.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/_shape_op_subprocess.py:10`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: parent bounds it with ``subprocess.run(timeout=...)`` so an un-interruptible native call is killed cleanly instead of SI
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/_shape_op_subprocess.py
high Shell/command execution in server code (src/build123d_mcp/_tessellate_subprocess.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/_tessellate_subprocess.py:12`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: ent can hard-kill via ``subprocess.run(timeout=...)``. Mirrors the export mesh gate (``_gate_subprocess``). """ import
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/_tessellate_subprocess.py
high Shell/command execution in server code (src/build123d_mcp/_vtk_render_subprocess_worker.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/_vtk_render_subprocess_worker.py:11`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: ent can hard-kill via ``subprocess.run(timeout=...)``. Mirrors ``_tessellate_subprocess`` (#357/#308). """ import pickl
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/_vtk_render_subprocess_worker.py
high Shell/command execution in server code (src/build123d_mcp/security.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/security.py:4`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: o layers applied before exec() is called: 1. AST inspection — rejects dangerous imports and calls. 2. Restricted bu
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/security.py
high Shell/command execution in server code (src/build123d_mcp/session.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/session.py:806`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: r(buf): exec(compiled, self.namespace) # noqa: S102 # Cancel alarm immediately so it cannot
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/session.py
high Shell/command execution in server code (src/build123d_mcp/tools/_bounded.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/tools/_bounded.py:115`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: try: proc = subprocess.run( [ sys.executable, "-m",
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/tools/_bounded.py
high Shell/command execution in server code (src/build123d_mcp/tools/design_audit.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/tools/design_audit.py:137`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: try: proc = subprocess.run( [sys.executable, "-m", "build123d_mcp._design_audit_subprocess",
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/tools/design_audit.py
high Shell/command execution in server code (src/build123d_mcp/tools/library.py)MTC-SRC-002
In the server's implementation (`src/build123d_mcp/tools/library.py:160`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: tricted_builtins()} exec(compile(source, entry["path"], "exec"), namespace) # noqa: S102 if "make" not in name
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/tools/library.py
medium Unsafe deserialization (src/build123d_mcp/_vtk_render_subprocess_worker.py)MTC-SRC-007
In the server's implementation (`src/build123d_mcp/_vtk_render_subprocess_worker.py:22`): Deserializing untrusted data with these APIs can execute arbitrary code (a well-known RCE gadget class). This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.
Evidence: ") as f: args = pickle.load(f) png = _vtk_render_tesselated( args["shape_data"], args["dire
Fix: Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.
Location: server src/build123d_mcp/_vtk_render_subprocess_worker.py
Tools 38
Each tool and what it can reach — statically extracted from the published source.
exportnetwork egressanalyze_printabilityno sensitive capabilitycompareno sensitive capabilitycrop_drawingno sensitive capabilitycross_sectionsno sensitive capabilitydesign_auditno sensitive capabilitydestroy_sessionno sensitive capabilityexecuteno sensitive capabilityexecute_fileno sensitive capabilityfind_bored_bossesno sensitive capability
Show 28 more tools ↓
find_bossesno sensitive capabilityfind_countersinksno sensitive capabilityfind_hole_patternsno sensitive capabilityfind_holesno sensitive capabilityhealth_checkno sensitive capabilityimport_cad_fileno sensitive capabilityinspect_partno sensitive capabilityinstall_skillno sensitive capabilitylast_errorno sensitive capabilitylist_sessionsno sensitive capabilityload_partno sensitive capabilitylocate_gate_defectsno sensitive capabilitymeasureno sensitive capabilityprepare_drawingno sensitive capabilityrecognise_featuresno sensitive capabilityrender_viewno sensitive capabilityrepair_adviceno sensitive capabilityrepair_hintsno sensitive capabilityresetno sensitive capabilityresolveno sensitive capabilityrestore_snapshotno sensitive capabilitysave_snapshotno sensitive capabilityscriptno sensitive capabilitysearch_libraryno sensitive capabilitysession_stateno sensitive capabilityvalidateno sensitive capabilityversionno sensitive capabilityworkflow_hintsno sensitive capability
What this scan could not see
- Tools were statically extracted from the published source (38 recovered), not enumerated from a running server. Tool-poisoning, Unicode-smuggling, capability and toxic-flow analysis ran on this inferred surface, but a mis-parsed registration could be missed or mis-attributed, so tool-derived findings are capped below “confirmed”. To grade the real runtime surface, scan the running server: --command "npx -y <package>".
Versions 6
Scan history per published version. The engine is deterministic — the same version always yields the same score, so a changed score means the package itself changed.
| Version | Score | Findings | Engine | Scanned |
|---|---|---|---|---|
v0.3.84 latest |
B 87/100 | 13 | 1.13.0 | 2026-09-05 |
v0.3.83 |
B 87/100 | 13 | 1.13.0 | 2026-08-29 |
v0.3.82 |
B 87/100 | 14 | 1.13.0 | 2026-08-25 |
v0.3.81 |
B 87/100 | 14 | 1.12.1 | 2026-08-03 |
v0.3.80 |
B 87/100 | 14 | 1.12.1 | 2026-07-27 |
Show 1 more version ↓
v0.3.79 |
B 87/100 | 14 | 1.9.0 | 2026-07-23 |
Embed this score
Show this server's live Trust Score in your README, docs or website. The badge is served straight from the registry and updates automatically after every rescan — no API key needed. It links back to this page, so anyone who sees the grade can also read the findings behind it instead of taking a number on faith.
Verify this score yourself
The score above is reproducible: the same package version always yields the same result. Run it locally or over the free API — no account, no LLM, fully deterministic.
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