Apache Log4j Core: verifyHostName attribute silently ignored in TLS configuration, allowing hostname verification bypass_CVE-2026-34477

{
    "lastseen": "",
    "description": "The fix for  CVE-2025-68161 https://logging.apache.org/security.html#CVE-2025-68161  was incomplete: it addressed hostname verification only when enabled via the  log4j2.sslVerifyHostName https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.sslVerifyHostName  system property, but not when configured through the  verifyHostName https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName  attribute of the <Ssl> element.\n\nAlthough the verifyHostName configuration attribute was introduced in Log4j Core 2.12.0, it was silently ignored in all versions through 2.25.3, leaving TLS connections vulnerable to interception regardless of the configured value.\n\nA network-based attacker may be able to perform a man-in-the-middle attack when all of the following conditions are met:\n\n  *  An SMTP, Socket, or Syslog appender is in use.\n  *  TLS is configured via a nested <Ssl> element.\n  *  The attacker can present a certificate issued by a CA trusted by the appender's configured trust store, or by the default Java trust store if none is configured.\nThis issue does not affect users of the HTTP appender, which uses a separate  verifyHostname https://logging.apache.org/log4j/2.x/manual/appenders/network.html#HttpAppender-attr-verifyHostName  attribute that was not subject to this bug and verifies host names by default.\n\nUsers are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue.",
    "published": "2026-04-10T15:36:19.740Z",
    "modified": "2026-04-10T17:38:57.154Z",
    "type": "cve",
    "title": "Apache Log4j Core: verifyHostName attribute silently ignored in TLS configuration, allowing hostname verification bypass",
    "source": "apache",
    "references": "https://github.com/apache/logging-log4j2/pull/4075\nhttps://logging.apache.org/security.html#CVE-2026-34477\nhttps://logging.apache.org/cyclonedx/vdr.xml\nhttps://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName\nhttps://lists.apache.org/thread/lkx8cl46t2bvkcwfcb2pd43ygc097lq4",
    "id": "CVE-2026-34477",
    "bulletinFamily": "",
    "cwe": [
        "CWE-297"
    ],
    "cvelist": null,
    "sourceData": "Apache Software Foundation Apache Log4j Core 2.12.0\nApache Software Foundation Apache Log4j Core 3.0.0-alpha1",
    "sourceHref": "",
    "cvss": {
        "score": 6.3,
        "severity": "MEDIUM",
        "vector": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:L/SA:N",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Apache Log4j Core",
    "version": "2.12.0",
    "vendor": "Apache Software Foundation",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}