« Volver al listado

CVE-2026-34480

Estado: AnalizadaMedia (6.9)—

Apache Log4j Core's XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout , in versions up to and including 2.25.3, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets producing invalid XML output whenever a log message or MDC value contains such characters.

The impact depends on the StAX implementation in use:

Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue by sanitizing forbidden characters before XML output.

Detalles técnicos trazas, registros y código del informe original
  *  JRE built-in StAX: Forbidden characters are silently written to the output, producing malformed XML. Conforming parsers must reject such documents with a fatal error, which may cause downstream log-processing systems to drop the affected records.
  *  Alternative StAX implementations (e.g.,  Woodstox https://github.com/FasterXML/woodstox , a transitive dependency of the Jackson XML Dataformat module): An exception is thrown during the logging call, and the log event is never delivered to its intended appender, only to Log4j's internal status logger.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Apache — Log4j

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-34480",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-34480",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-04-10T17:43:51.255638Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "security@apache.org",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 6.9,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "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/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",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "LOW",
          "vulnIntegrityImpact": "NONE",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "security@apache.org",
      "affectedData": [
        {
          "cpes": [
            "cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*"
          ],
          "vendor": "Apache Software Foundation",
          "product": "Apache Log4j Core",
          "versions": [
            {
              "status": "affected",
              "version": "2.0-alpha1",
              "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-core",
          "packageName": "org.apache.logging.log4j:log4j-core",
          "collectionURL": "https://repo.maven.apache.org/maven2",
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-04-10T16:16:31.463",
  "references": [
    {
      "url": "https://github.com/apache/logging-log4j2/pull/4077",
      "tags": [
        "Issue Tracking",
        "Patch"
      ],
      "source": "security@apache.org"
    },
    {
      "url": "https://lists.apache.org/thread/5x0hcnng0chhghp6jgjdp3qmbbhfjzhb",
      "tags": [
        "Mailing List",
        "Vendor Advisory"
      ],
      "source": "security@apache.org"
    },
    {
      "url": "https://logging.apache.org/cyclonedx/vdr.xml",
      "tags": [
        "Product"
      ],
      "source": "security@apache.org"
    },
    {
      "url": "https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout",
      "tags": [
        "Technical Description"
      ],
      "source": "security@apache.org"
    },
    {
      "url": "https://logging.apache.org/security.html#CVE-2026-34480",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security@apache.org"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2026/04/10/9",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security@apache.org",
      "description": [
        {
          "lang": "en",
          "value": "CWE-116"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Apache Log4j Core's  XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout , in versions up to and including 2.25.3, fails to sanitize characters forbidden by the  XML 1.0 specification https://www.w3.org/TR/xml/#charsets  producing invalid XML output whenever a log message or MDC value contains such characters.\n\nThe impact depends on the StAX implementation in use:\n\n  *  JRE built-in StAX: Forbidden characters are silently written to the output, producing malformed XML. Conforming parsers must reject such documents with a fatal error, which may cause downstream log-processing systems to drop the affected records.\n  *  Alternative StAX implementations (e.g.,  Woodstox https://github.com/FasterXML/woodstox , a transitive dependency of the Jackson XML Dataformat module): An exception is thrown during the logging call, and the log event is never delivered to its intended appender, only to Log4j's internal status logger.\n\n\nUsers are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue by sanitizing forbidden characters before XML output."
    }
  ],
  "lastModified": "2026-06-17T10:39:07.087",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "EB58E4E0-0D2E-4565-9436-5191B31DEB6B",
              "versionEndExcluding": "2.25.4",
              "versionStartIncluding": "2.0"
            },
            {
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "5EE518C3-2F43-40FF-B754-C340B7003FC7"
            },
            {
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "6D2A01C1-D56C-4198-8ADB-11739F791E2B"
            },
            {
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "D6F8BD61-DD30-4D64-842C-850E5B117036"
            },
            {
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "ED00C38D-27EA-489C-9A2B-3594ACA8A3C5"
            },
            {
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "8794D719-1D90-4378-B48B-698EA40FBFB2"
            },
            {
              "criteria": "cpe:2.3:a:apache:log4j:3.0.0:beta3:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "74C9FCBD-ECAD-4C29-B97A-2B9D97C0FC1F"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "security@apache.org"
}