Wazuh: Pre-auth stack-based buffer overflow in wazuh-remoted print_hex_string() due to signed char promotion on x86_64_CVE-2026-28221

{
    "lastseen": "",
    "description": "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 \u201cunexpected message (hex)\u201d 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.",
    "published": "2026-04-29T17:53:15.374Z",
    "modified": "2026-04-29T18:34:59.895Z",
    "type": "cve",
    "title": "Wazuh: Pre-auth stack-based buffer overflow in wazuh-remoted print_hex_string() due to signed char promotion on x86_64",
    "source": "GitHub_M",
    "references": "https://github.com/wazuh/wazuh/security/advisories/GHSA-q9vv-7w4c-f4cm\nhttps://github.com/wazuh/wazuh/releases/tag/v4.14.4",
    "id": "CVE-2026-28221",
    "bulletinFamily": "",
    "cwe": [
        "CWE-121",
        "CWE-400"
    ],
    "cvelist": null,
    "sourceData": "wazuh wazuh >= 4.8.0, < 4.14.4",
    "sourceHref": "",
    "cvss": {
        "score": 6.5,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
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        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
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            "baseScore": 0,
            "baseSeverity": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "wazuh",
    "version": ">= 4.8.0, < 4.14.4",
    "vendor": "wazuh",
    "ai_description": "",
    "ai_severity": "",
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    "ai_score": 0
}