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          "dateUpdated": "2026-04-10T16:18:18.699Z",
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        },
        "references": [
          {
            "url": "http://www.openwall.com/lists/oss-security/2026/04/10/8"
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        ],
        "title": "CVE Program Container"
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        "metrics": [
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            "other": {
              "content": {
                "id": "CVE-2026-34479",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-10T17:45:24.466114Z",
                "version": "2.0.3"
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              "type": "ssvc"
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        "providerMetadata": {
          "dateUpdated": "2026-04-10T17:47:34.402Z",
          "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_1_2_api:*:*:*:*:*:*:*:*"
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          "defaultStatus": "unaffected",
          "packageName": "org.apache.logging.log4j:log4j-1.2-api",
          "packageURL": "pkg:maven/org.apache.logging.log4j/log4j-1.2-api",
          "product": "Apache Log4j 1 to Log4j 2 bridge",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThan": "2.25.4",
              "status": "affected",
              "version": "2.7",
              "versionType": "maven"
            },
            {
              "lessThanOrEqual": "3.0.0-beta2",
              "status": "affected",
              "version": "3.0.0-alpha1",
              "versionType": "maven"
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          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Ap4sh (Samy Medjahed) and Ethicxz (Eliott Laurie) (original reporters)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "jabaltarik1 (independently)"
        }
      ],
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              "value": "\u003cp\u003eThe \u003ccode\u003eLog4j1XmlLayout\u003c/code\u003e 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.\u003c/p\u003e\u003cp\u003eTwo groups of users are affected:\u003c/p\u003e\u003cul\u003e\u003cli\u003eThose using \u003ccode\u003eLog4j1XmlLayout\u003c/code\u003e directly in a Log4j Core 2 configuration file.\u003c/li\u003e\u003cli\u003eThose using the Log4j 1 configuration compatibility layer with \u003ccode\u003eorg.apache.log4j.xml.XMLLayout\u003c/code\u003e specified as the layout class.\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eUsers are advised to upgrade to Apache Log4j 1-to-Log4j 2 bridge version 2.25.4, which corrects this issue.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eNote:\u003c/strong\u003e The Apache Log4j 1-to-Log4j 2 bridge is deprecated and will not be present in Log4j 3. Users are encouraged to consult the \u003ca target=\"_blank\" rel=\"nofollow\" href=\"https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html\"\u003eLog4j 1 to Log4j 2 migration guide\u003c/a\u003e, and specifically the section on eliminating reliance on the bridge.\u003c/p\u003e"
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            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "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:L/AT:N/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"
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          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
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        },
        {
          "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"
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          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-10T15:41:07.888Z",
        "orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
        "shortName": "apache"
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        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/apache/logging-log4j2/pull/4078"
        },
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          "tags": [
            "vendor-advisory"
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          "url": "https://logging.apache.org/security.html#CVE-2026-34479"
        },
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://logging.apache.org/cyclonedx/vdr.xml"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html"
        },
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.apache.org/thread/gd0hp6mj17rn3kj279vgy4p7kd4zz5on"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
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      "timeline": [
        {
          "lang": "en",
          "time": "2026-02-16T17:11:00.000Z",
          "value": "Vulnerability reported by Ap4sh and ethicxz"
        },
        {
          "lang": "en",
          "time": "2026-03-15T05:39:00.000Z",
          "value": "Independent report received from jabaltarik1"
        },
        {
          "lang": "en",
          "time": "2026-03-24T18:56:00.000Z",
          "value": "Fix shared publicly by Piotr P. Karwasz as pull request #4078"
        },
        {
          "lang": "en",
          "time": "2026-03-25T09:46:00.000Z",
          "value": "Fix verified by reporter"
        },
        {
          "lang": "en",
          "time": "2026-03-28T11:19:00.000Z",
          "value": "Log4j 2.25.4 released"
        }
      ],
      "title": "Apache Log4j 1 to Log4j 2 bridge: Silent log event loss in Log4j1XmlLayout due to unescaped XML 1.0 forbidden characters",
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    "dateReserved": "2026-03-28T14:06:31.965Z",
    "dateUpdated": "2026-04-10T17:47:34.402Z",
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