FKIE_CVE-2026-40023

Vulnerability from fkie_nvd - Published: 2026-04-10 16:16 - Updated: 2026-06-17 10:44
Severity
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Summary
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.
References
security@apache.orghttps://github.com/apache/logging-log4cxx/pull/609Issue Tracking, Patch
security@apache.orghttps://lists.apache.org/thread/y15cv3zblg3dfwr5vy6ddbnl4zyrzr8bMailing List, Vendor Advisory
security@apache.orghttps://logging.apache.org/cyclonedx/vdr.xmlProduct
security@apache.orghttps://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.htmlProduct
security@apache.orghttps://logging.apache.org/security.html#CVE-2026-40023Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/04/10/12Mailing List, Third Party Advisory
Impacted products
Vendor Product Version
apache log4cxx *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "cpes": [
            "cpe:2.3:a:apache:log4cxx:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "product": "Apache Log4cxx",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThan": "1.7.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://conan.io/center",
          "defaultStatus": "unaffected",
          "packageName": "log4cxx",
          "packageURL": "pkg:conan/log4cxx",
          "product": "Apache Log4cxx (Conan)",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThan": "1.7.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://brew.sh/",
          "defaultStatus": "unaffected",
          "packageName": "log4cxx",
          "product": "Apache Log4cxx (Brew)",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThan": "1.7.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "security@apache.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:apache:log4cxx:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "8ACE57FE-D5F6-4875-976B-7EFADC4F714A",
              "versionEndExcluding": "1.7.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Apache Log4cxx\u0027s  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."
    }
  ],
  "id": "CVE-2026-40023",
  "lastModified": "2026-06-17T10:44:37.067",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "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: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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security@apache.org",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-40023",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-10T17:28:20.094265Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-10T16:16:32.600",
  "references": [
    {
      "source": "security@apache.org",
      "tags": [
        "Issue Tracking",
        "Patch"
      ],
      "url": "https://github.com/apache/logging-log4cxx/pull/609"
    },
    {
      "source": "security@apache.org",
      "tags": [
        "Mailing List",
        "Vendor Advisory"
      ],
      "url": "https://lists.apache.org/thread/y15cv3zblg3dfwr5vy6ddbnl4zyrzr8b"
    },
    {
      "source": "security@apache.org",
      "tags": [
        "Product"
      ],
      "url": "https://logging.apache.org/cyclonedx/vdr.xml"
    },
    {
      "source": "security@apache.org",
      "tags": [
        "Product"
      ],
      "url": "https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.html"
    },
    {
      "source": "security@apache.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://logging.apache.org/security.html#CVE-2026-40023"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "url": "http://www.openwall.com/lists/oss-security/2026/04/10/12"
    }
  ],
  "sourceIdentifier": "security@apache.org",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-116"
        }
      ],
      "source": "security@apache.org",
      "type": "Secondary"
    }
  ]
}



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