CVE-2026-34477

Full vulnerability record from the local CVENow database.

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. Although 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. A network-based attacker may be able to perform a man-in-the-middle attack when all of the following conditions are met: * An SMTP, Socket, or Syslog appender is in use. * TLS is configured via a nested <Ssl> element. * 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. This 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. Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue.

Severity

MEDIUM

CVSS score

6.3 (v4.0)

Vulnerability status

Analyzed

Source identifier

[email protected]

Published

2026-04-10 16:16:30.843000

Last modified

2026-10-26 22:10:00.163000

View original CVE JSON

{
  "id": "CVE-2026-34477",
  "sourceIdentifier": "[email protected]",
  "published": "2026-04-10T16:16:30.843",
  "lastModified": "2026-10-26T22:10:00.163",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "La corrección para CVE-2025-68161 https://logging.apache.org/security.html#CVE-2025-68161 fue incompleta: abordaba la verificación del nombre de host solo cuando se habilitaba a través de la propiedad del sistema log4j2.sslVerifyHostName https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.sslVerifyHostName, pero no cuando se configuraba a través del atributo verifyHostName https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName del elemento [Ssl].\n\nAunque el atributo de configuración verifyHostName se introdujo en Log4j Core 2.12.0, fue ignorado silenciosamente en todas las versiones hasta la 2.25.3, dejando las conexiones TLS vulnerables a la intercepción independientemente del valor configurado.\n\nUn atacante basado en red podría realizar un ataque man-in-the-middle cuando se cumplen todas las siguientes condiciones:\n\n  *  Se está utilizando un appender SMTP, Socket o Syslog.\n  *  TLS está configurado a través de un elemento [Ssl] anidado.\n  *  El atacante puede presentar un certificado emitido por una CA de confianza para el almacén de confianza configurado del appender, o por el almacén de confianza predeterminado de Java si no hay ninguno configurado.\nEste problema no afecta a los usuarios del appender HTTP, que utiliza un atributo verifyHostname https://logging.apache.org/log4j/2.x/manual/appenders/network.html#HttpAppender-attr-verifyHostName separado que no estaba sujeto a este error y verifica los nombres de host por defecto.\n\nSe aconseja a los usuarios actualizar a Apache Log4j Core 2.25.4, que corrige este problema."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
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          "product": "Apache Log4j Core",
          "defaultStatus": "unaffected",
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          "packageName": "org.apache.logging.log4j:log4j-core",
          "cpes": [
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          "packageURL": "pkg:maven/org.apache.logging.log4j/log4j-core",
          "versions": [
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              "lessThan": "2.25.4",
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              "status": "affected"
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  "metrics": {
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        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
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          "baseScore": 6.3,
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          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
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          "vulnConfidentialityImpact": "LOW",
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          "vulnAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "LOW",
          "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": [
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        "source": "[email protected]",
        "type": "Primary",
        "cvssData": {
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          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "availabilityImpact": "NONE"
        },
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        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-04-10T17:36:46.652477Z",
          "id": "CVE-2026-34477",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-297"
        }
      ]
    },
    {
      "source": "[email protected]",
      "type": "Primary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-295"
        }
      ]
    }
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          "negate": false,
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      "source": "[email protected]",
      "tags": [
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        "Patch"
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      "source": "[email protected]",
      "tags": [
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      "url": "https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName",
      "source": "[email protected]",
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    {
      "url": "https://logging.apache.org/security.html#CVE-2026-34477",
      "source": "[email protected]",
      "tags": [
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    }
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}