CVE-2026-40023
Full vulnerability record from the local CVENow database.
Description
Apache Log4cxx's XMLLayout https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.html , in versions before 1.7.0, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets in log messages, NDC, and MDC property keys and values, producing invalid XML output. Conforming XML parsers must reject such documents with a fatal error, which may cause downstream log processing systems to drop or fail to index affected records. An attacker who can influence logged data can exploit this to suppress individual log records, impairing audit trails and detection of malicious activity. Users are advised to upgrade to Apache Log4cxx 1.7.0, which fixes this issue.
Severity
MEDIUM
CVSS score
6.3
(v4.0)
Vulnerability status
Analyzed
Source identifier
Published
2026-04-10 16:16:32.600000
Last modified
2026-10-26 21:10:00.170000
View original CVE JSON
{
"id": "CVE-2026-40023",
"sourceIdentifier": "[email protected]",
"published": "2026-04-10T16:16:32.600",
"lastModified": "2026-10-26T21:10:00.170",
"vulnStatus": "Analyzed",
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"value": "Apache Log4cxx's XMLLayout https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.html , in versions before 1.7.0, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets in log messages, NDC, and MDC property keys and values, producing invalid XML output. Conforming XML parsers must reject such documents with a fatal error, which may cause downstream log processing systems to drop or fail to index affected records.\n\nAn attacker who can influence logged data can exploit this to suppress individual log records, impairing audit trails and detection of malicious activity.\n\nUsers are advised to upgrade to Apache Log4cxx 1.7.0, which fixes this issue."
},
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"lang": "es",
"value": "El XMLLayout de Apache Log4cxx https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.html , en versiones anteriores a la 1.7.0, no logra sanear los caracteres prohibidos por la especificación XML 1.0 https://www.w3.org/TR/xml/#charsets en los mensajes de registro, y en las claves y valores de las propiedades NDC y MDC, produciendo una salida XML no válida. Los analizadores XML conformes deben rechazar dichos documentos con un error fatal, lo que puede provocar que los sistemas de procesamiento de registros posteriores descarten o no indexen los registros afectados.\n\nUn atacante que puede influir en los datos registrados puede explotar esto para suprimir registros de log individuales, lo que perjudica las pistas de auditoría y la detección de actividad maliciosa.\n\nSe aconseja a los usuarios actualizar a Apache Log4cxx 1.7.0, que corrige este problema."
}
],
"affected": [
{
"source": "[email protected]",
"affectedData": [
{
"vendor": "Apache Software Foundation",
"product": "Apache Log4cxx",
"defaultStatus": "unaffected",
"cpes": [
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"type": "Secondary",
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"baseScore": 6.3,
"baseSeverity": "MEDIUM",
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"subAvailabilityImpact": "NONE",
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"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",
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"valueDensity": "NOT_DEFINED",
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"cvssMetricV31": [
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"id": "CVE-2026-40023",
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"version": "2.0.3"
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"weaknesses": [
{
"source": "[email protected]",
"type": "Secondary",
"description": [
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"lang": "en",
"value": "CWE-116"
}
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"source": "[email protected]",
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