CVE-2026-8449

#!/usr/bin/env python3 """ PoC for CVE-2026-8449: Linux ksmbd Remote Memory Corruption via ACL Inheritance This script demonstrates the logic of triggering the vulnerability by setting a malformed DACL. Note: Actual exploitation requires precise memory layout control. """ import socket import struct # Simplified pseudo-code for the attack flow # 1. Connect to SMB server # 2. Authenticate and get Tree Connect # 3. Create a directory # 4. Craft SMB2_SET_INFO request with a malformed DACL # The DACL contains a SID with an inflated 'num_subauth' field. MALFORMED_SID = b"\x01\x00\x00\x00" + b"\x00\x00\x00\x00" + b"\xFF\xFF" # Example malformed SID structure def trigger_vulnerability(target_ip, username, password): print(f"[*] Connecting to {target_ip}...") # Implementation of SMB handshake and auth would go here (using impacket or similar) print("[*] Creating directory...") # SMB2_CREATE request for a directory print("[*] Setting malicious DACL via SMB2_SET_INFO...") # SMB2_SET_INFO request # SecurityInfo field = 0x04 (DACL_SECURITY_INFORMATION) # Buffer contains the MALFORMED_SID print("[*] Creating child entry to trigger inheritance...") # SMB2_CREATE request inside the previous directory # This triggers ksmbd to parse the parent ACL, leading to OOB Read print("[+] Trigger sent. Check target kernel status.") if __name__ == "__main__": # Usage: python3 poc.py <TARGET_IP> <USER> <PASS> pass

{"cve": {"id": "CVE-2026-8449", "sourceIdentifier": "[email protected]", "published": "2026-05-12T22:16:38.730", "lastModified": "2026-05-12T22:16:38.730", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "Linux ksmbd contains a remote memory corruption vulnerability in the ACL inheritance path that allows remote clients with directory creation permissions to trigger a heap out-of-bounds read and subsequent heap corruption by setting a crafted DACL with a malformed SID containing an inflated num_subauth field. Attackers can exploit this vulnerability by creating a directory, setting the malicious DACL via SMB2_SET_INFO, and creating child entries to cause kernel instability, denial of service, or potentially achieve privilege escalation to kernel code execution."}], "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: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": 8.7, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "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:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-125"}]}], "references": [{"url": "https://github.com/torvalds/linux/blob/6596a02b207886e9e00bb0161c7fd59fea53c081/fs/smb/server/smbacl.c", "source": "[email protected]"}, {"url": "https://github.com/torvalds/linux/commit/996454bc0da84d5a1dedb1a7861823087e01a7ae", "source": "[email protected]"}, {"url": "https://www.vulncheck.com/advisories/linux-ksmbd-remote-memory-corruption-via-acl-inheritance", "source": "[email protected]"}]}}