CVE-2026-34479

{
  "id": "CVE-2026-34479",
  "sourceIdentifier": "[email protected]",
  "published": "2026-04-10T16:16:31.270",
  "lastModified": "2026-10-26T21:10:00.170",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The Log4j1XmlLayout from the Apache Log4j 1-to-Log4j 2 bridge fails to escape characters forbidden by the XML 1.0 standard, producing malformed XML output. Conforming XML parsers are required to reject documents containing such characters with a fatal error, which may cause downstream log processing systems to drop or fail to index affected records.\n\nTwo groups of users are affected:\n\n  *  Those using Log4j1XmlLayout directly in a Log4j Core 2 configuration file.\n  *  Those using the Log4j 1 configuration compatibility layer with org.apache.log4j.xml.XMLLayout specified as the layout class.\n\n\nUsers are advised to upgrade to Apache Log4j 1-to-Log4j 2 bridge version 2.25.4, which corrects this issue.\n\nNote: The Apache Log4j 1-to-Log4j 2 bridge is deprecated and will not be present in Log4j 3. Users are encouraged to consult the  Log4j 1 to Log4j 2 migration guide https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html , and specifically the section on eliminating reliance on the bridge."
    },
    {
      "lang": "es",
      "value": "El Log4j1XmlLayout del puente Apache Log4j 1-a-Log4j 2 no logra escapar caracteres prohibidos por el estándar XML 1.0, produciendo una salida XML mal formada. Los analizadores XML conformes deben rechazar documentos que contengan dichos caracteres con un error fatal, lo que puede causar que los sistemas de procesamiento de registros posteriores descarten o no logren indexar los registros afectados.\n\nDos grupos de usuarios se ven afectados:\n\n  *  Aquellos que utilizan Log4j1XmlLayout directamente en un archivo de configuración de Log4j Core 2.\n  *  Aquellos que utilizan la capa de compatibilidad de configuración de Log4j 1 con org.apache.log4j.xml.XMLLayout especificado como la clase de diseño.\n\nSe aconseja a los usuarios actualizar al puente Apache Log4j 1-a-Log4j 2 versión 2.25.4, que corrige este problema.\n\nNota: El puente Apache Log4j 1-a-Log4j 2 está obsoleto y no estará presente en Log4j 3. Se anima a los usuarios a consultar la guía de migración de Log4j 1 a Log4j 2 https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html, y específicamente la sección sobre la eliminación de la dependencia del puente."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "Apache Software Foundation",
          "product": "Apache Log4j 1 to Log4j 2 bridge",
          "defaultStatus": "unaffected",
          "collectionURL": "https://repo.maven.apache.org/maven2",
          "packageName": "org.apache.logging.log4j:log4j-1.2-api",
          "cpes": [
            "cpe:2.3:a:apache:log4j_1_2_api:*:*:*:*:*:*:*:*"
          ],
          "packageURL": "pkg:maven/org.apache.logging.log4j/log4j-1.2-api",
          "versions": [
            {
              "version": "2.7",
              "lessThan": "2.25.4",
              "versionType": "maven",
              "status": "affected"
            },
            {
              "version": "3.0.0-alpha1",
              "lessThanOrEqual": "3.0.0-beta2",
              "versionType": "maven",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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": 6.9,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "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": [
      {
        "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:H/A:N",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-04-10T17:45:24.466114Z",
          "id": "CVE-2026-34479",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-116"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*",
              "versionStartIncluding": "2.7",
              "versionEndExcluding": "2.25.4",
              "matchCriteriaId": "4D7C1729-01D6-4981-B3FB-3A877083AE28"
            },
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:*",
              "matchCriteriaId": "5EE518C3-2F43-40FF-B754-C340B7003FC7"
            },
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:*",
              "matchCriteriaId": "6D2A01C1-D56C-4198-8ADB-11739F791E2B"
            },
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:*",
              "matchCriteriaId": "D6F8BD61-DD30-4D64-842C-850E5B117036"
            },
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:*",
              "matchCriteriaId": "ED00C38D-27EA-489C-9A2B-3594ACA8A3C5"
            },
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:*",
              "matchCriteriaId": "8794D719-1D90-4378-B48B-698EA40FBFB2"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/apache/logging-log4j2/pull/4078",
      "source": "[email protected]",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Patch"
      ]
    },
    {
      "url": "https://lists.apache.org/thread/gd0hp6mj17rn3kj279vgy4p7kd4zz5on",
      "source": "[email protected]",
      "tags": [
        "Mailing List"
      ]
    },
    {
      "url": "https://logging.apache.org/cyclonedx/vdr.xml",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html",
      "source": "[email protected]",
      "tags": [
        "Mitigation"
      ]
    },
    {
      "url": "https://logging.apache.org/security.html#CVE-2026-34479",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2026/04/10/8",
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Mailing List"
      ]
    }
  ]
}