CVE-2026-34481

Full vulnerability record from the local CVENow database.

Description

Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (NaN, Infinity, or -Infinity), which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to index affected records. An attacker can exploit this issue only if both of the following conditions are met: * The application uses JsonTemplateLayout. * The application logs a MapMessage, or logs an object directly (e.g., via Logger.info(Object), which wraps it in an ObjectMessage), where the message contains an attacker-controlled floating-point value. Users are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue. Note: The fix released in version 2.25.4 did not cover all affected code paths. CVE-2026-49844 was assigned to the remaining issue, which concerns the MapMessage.asJson() serialization in Apache Log4j API and is fixed in versions 2.25.5 and 2.26.1.

Severity

MEDIUM

CVSS score

6.3 (v4.0)

Vulnerability status

Modified

Source identifier

[email protected]

Published

2026-04-10 16:16:31.663000

Last modified

2026-10-26 22:10:00.163000

View original CVE JSON

{
  "id": "CVE-2026-34481",
  "sourceIdentifier": "[email protected]",
  "published": "2026-04-10T16:16:31.663",
  "lastModified": "2026-10-26T22:10:00.163",
  "vulnStatus": "Modified",
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      "lang": "en",
      "value": "Apache Log4j's  JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (NaN, Infinity, or -Infinity), which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to index affected records.\n\nAn attacker can exploit this issue only if both of the following conditions are met:\n\n  *  The application uses JsonTemplateLayout.\n  *  The application logs a MapMessage, or logs an object directly (e.g., via Logger.info(Object), which wraps it in an ObjectMessage), where the message contains an attacker-controlled floating-point value.\n\n\nUsers are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.\n\nNote: The fix released in version 2.25.4 did not cover all affected code paths. CVE-2026-49844 was assigned to the remaining issue, which concerns the MapMessage.asJson() serialization in Apache Log4j API and is fixed in versions 2.25.5 and 2.26.1."
    },
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      "lang": "es",
      "value": "El JsonTemplateLayout de Apache Log4j https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , en versiones hasta la 2.25.3 inclusive, produce una salida JSON no válida cuando los eventos de registro contienen valores de punto flotante no finitos (NaN, Infinity o -Infinity), los cuales están prohibidos por el RFC 8259. Esto puede hacer que los sistemas de procesamiento de registros posteriores rechacen o no puedan indexar los registros afectados.\n\nUn atacante puede explotar este problema solo si se cumplen las dos condiciones siguientes:\n\n  *  La aplicación utiliza JsonTemplateLayout.\n  *  La aplicación registra un MapMessage que contiene un valor de punto flotante controlado por el atacante.\n\nSe aconseja a los usuarios actualizar a Apache Log4j JSON Template Layout 2.25.4, que corrige este problema."
    }
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      "source": "[email protected]",
      "affectedData": [
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          "product": "Apache Log4j JSON Template Layout",
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          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
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