CVE-2026-34481 (GCVE-0-2026-34481)
Vulnerability from cvelistv5
Published
2026-04-10 15:43
Modified
2026-07-11 04:55
Severity ?
6.3 (Medium) - CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
CWE
  • CWE-116 - Improper Encoding or Escaping of Output
Summary
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.
References
Impacted products
Vendor Product Version
Apache Software Foundation Apache Log4j JSON Template Layout Version: 2.14.0
Version: 3.0.0-alpha1
    cpe:2.3:a:apache:log4j_layout_template_json:*:*:*:*:*:*:*:*
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2026-04-10T16:18:20.891Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "http://www.openwall.com/lists/oss-security/2026/04/10/10"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-34481",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-10T17:41:23.224802Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-10T17:41:38.229Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://repo.maven.apache.org/maven2",
          "cpes": [
            "cpe:2.3:a:apache:log4j_layout_template_json:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "packageName": "org.apache.logging.log4j:log4j-layout-template-json",
          "packageURL": "pkg:maven/org.apache.logging.log4j/log4j-layout-template-json",
          "product": "Apache Log4j JSON Template Layout",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThan": "2.25.4",
              "status": "affected",
              "version": "2.14.0",
              "versionType": "maven"
            },
            {
              "lessThanOrEqual": "3.0.0-beta3",
              "status": "affected",
              "version": "3.0.0-alpha1",
              "versionType": "maven"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Ap4sh (Samy Medjahed) and Ethicxz (Eliott Laurie)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eApache Log4j\u0027s \u003ccode\u003e\u003ca target=\"_blank\" rel=\"nofollow\" href=\"https://logging.apache.org/log4j/2.x/manual/json-template-layout.html\"\u003eJsonTemplateLayout\u003c/a\u003e\u003c/code\u003e, in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (\u003ccode\u003eNaN\u003c/code\u003e, \u003ccode\u003eInfinity\u003c/code\u003e, or \u003ccode\u003e-Infinity\u003c/code\u003e), which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to index affected records.\u003c/p\u003e\u003cp\u003eAn attacker can exploit this issue only if both of the following conditions are met:\u003c/p\u003e\u003cul\u003e\u003cli\u003eThe application uses \u003ccode\u003eJsonTemplateLayout\u003c/code\u003e.\u003c/li\u003e\u003cli\u003eThe application logs a \u003ccode\u003eMapMessage\u003c/code\u003e, or logs an object directly (e.g., via \u003ccode\u003eLogger.info(Object)\u003c/code\u003e, which wraps it in an \u003ccode\u003eObjectMessage\u003c/code\u003e), where the message contains an attacker-controlled floating-point value.\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eUsers are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eNote:\u003c/strong\u003e 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 \u003ccode\u003eMapMessage.asJson()\u003c/code\u003e serialization in Apache Log4j API and is fixed in versions 2.25.5 and 2.26.1.\u003c/p\u003e"
            }
          ],
          "value": "Apache Log4j\u0027s  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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "LOW",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "other": {
            "content": {
              "text": "moderate"
            },
            "type": "Textual description of severity"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-116",
              "description": "CWE-116 Improper Encoding or Escaping of Output",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-11T04:55:42.502Z",
        "orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
        "shortName": "apache"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/apache/logging-log4j2/pull/4080"
        },
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://logging.apache.org/security.html#CVE-2026-34481"
        },
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://logging.apache.org/cyclonedx/vdr.xml"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://logging.apache.org/log4j/2.x/manual/json-template-layout.html"
        },
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "timeline": [
        {
          "lang": "en",
          "time": "2026-02-16T18:14:00.000Z",
          "value": "Vulnerability reported by Ap4sh and ethicxz"
        },
        {
          "lang": "en",
          "time": "2026-03-10T20:42:00.000Z",
          "value": "Candidate patch internally shared by Piotr P. Karwasz"
        },
        {
          "lang": "en",
          "time": "2026-03-24T23:06:00.000Z",
          "value": "Fix shared publicly by Piotr P. Karwasz as pull request #4080"
        },
        {
          "lang": "en",
          "time": "2026-03-25T09:54:00.000Z",
          "value": "Fix verified by the reporter"
        },
        {
          "lang": "en",
          "time": "2026-03-28T11:19:00.000Z",
          "value": "Log4j 2.25.4 released"
        }
      ],
      "title": "Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
    "assignerShortName": "apache",
    "cveId": "CVE-2026-34481",
    "datePublished": "2026-04-10T15:43:00.100Z",
    "dateReserved": "2026-03-28T19:23:37.127Z",
    "dateUpdated": "2026-07-11T04:55:42.502Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CVE Program Container\", \"references\": [{\"url\": \"http://www.openwall.com/lists/oss-security/2026/04/10/10\"}], \"providerMetadata\": {\"orgId\": \"af854a3a-2127-422b-91ae-364da2661108\", \"shortName\": \"CVE\", \"dateUpdated\": \"2026-04-10T16:18:20.891Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-34481\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-04-10T17:41:23.224802Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-04-10T17:41:31.864Z\"}}], \"cna\": {\"title\": \"Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout\", \"source\": {\"discovery\": \"EXTERNAL\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Ap4sh (Samy Medjahed) and Ethicxz (Eliott Laurie)\"}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 6.3, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"HIGH\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"LOW\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}, {\"other\": {\"type\": \"Textual description of severity\", \"content\": {\"text\": \"moderate\"}}}], \"affected\": [{\"cpes\": [\"cpe:2.3:a:apache:log4j_layout_template_json:*:*:*:*:*:*:*:*\"], \"vendor\": \"Apache Software Foundation\", \"product\": \"Apache Log4j JSON Template Layout\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.14.0\", \"lessThan\": \"2.25.4\", \"versionType\": \"maven\"}, {\"status\": \"affected\", \"version\": \"3.0.0-alpha1\", \"versionType\": \"maven\", \"lessThanOrEqual\": \"3.0.0-beta3\"}], \"packageURL\": \"pkg:maven/org.apache.logging.log4j/log4j-layout-template-json\", \"packageName\": \"org.apache.logging.log4j:log4j-layout-template-json\", \"collectionURL\": \"https://repo.maven.apache.org/maven2\", \"defaultStatus\": \"unaffected\"}], \"timeline\": [{\"lang\": \"en\", \"time\": \"2026-02-16T18:14:00.000Z\", \"value\": \"Vulnerability reported by Ap4sh and ethicxz\"}, {\"lang\": \"en\", \"time\": \"2026-03-10T20:42:00.000Z\", \"value\": \"Candidate patch internally shared by Piotr P. Karwasz\"}, {\"lang\": \"en\", \"time\": \"2026-03-24T23:06:00.000Z\", \"value\": \"Fix shared publicly by Piotr P. Karwasz as pull request #4080\"}, {\"lang\": \"en\", \"time\": \"2026-03-25T09:54:00.000Z\", \"value\": \"Fix verified by the reporter\"}, {\"lang\": \"en\", \"time\": \"2026-03-28T11:19:00.000Z\", \"value\": \"Log4j 2.25.4 released\"}], \"references\": [{\"url\": \"https://github.com/apache/logging-log4j2/pull/4080\", \"tags\": [\"patch\"]}, {\"url\": \"https://logging.apache.org/security.html#CVE-2026-34481\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://logging.apache.org/cyclonedx/vdr.xml\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://logging.apache.org/log4j/2.x/manual/json-template-layout.html\", \"tags\": [\"related\"]}, {\"url\": \"https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv\", \"tags\": [\"vendor-advisory\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Apache Log4j\u0027s  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.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eApache Log4j\u0027s \u003ccode\u003e\u003ca target=\\\"_blank\\\" rel=\\\"nofollow\\\" href=\\\"https://logging.apache.org/log4j/2.x/manual/json-template-layout.html\\\"\u003eJsonTemplateLayout\u003c/a\u003e\u003c/code\u003e, in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (\u003ccode\u003eNaN\u003c/code\u003e, \u003ccode\u003eInfinity\u003c/code\u003e, or \u003ccode\u003e-Infinity\u003c/code\u003e), which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to index affected records.\u003c/p\u003e\u003cp\u003eAn attacker can exploit this issue only if both of the following conditions are met:\u003c/p\u003e\u003cul\u003e\u003cli\u003eThe application uses \u003ccode\u003eJsonTemplateLayout\u003c/code\u003e.\u003c/li\u003e\u003cli\u003eThe application logs a \u003ccode\u003eMapMessage\u003c/code\u003e, or logs an object directly (e.g., via \u003ccode\u003eLogger.info(Object)\u003c/code\u003e, which wraps it in an \u003ccode\u003eObjectMessage\u003c/code\u003e), where the message contains an attacker-controlled floating-point value.\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eUsers are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eNote:\u003c/strong\u003e 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 \u003ccode\u003eMapMessage.asJson()\u003c/code\u003e serialization in Apache Log4j API and is fixed in versions 2.25.5 and 2.26.1.\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-116\", \"description\": \"CWE-116 Improper Encoding or Escaping of Output\"}]}], \"providerMetadata\": {\"orgId\": \"f0158376-9dc2-43b6-827c-5f631a4d8d09\", \"shortName\": \"apache\", \"dateUpdated\": \"2026-07-11T04:55:42.502Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-34481\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-07-11T04:55:42.502Z\", \"dateReserved\": \"2026-03-28T19:23:37.127Z\", \"assignerOrgId\": \"f0158376-9dc2-43b6-827c-5f631a4d8d09\", \"datePublished\": \"2026-04-10T15:43:00.100Z\", \"assignerShortName\": \"apache\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.