apache-log4j2 — security advisory

{
  "id": "663e9f569346acf51efc1310cb41624a0d57251c93dc68b1746f8ad361d300d6",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-34479",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-34479",
    "summary": "The Log4j1XmlLayout 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. Two groups of users are affected: * Those using Log4j1XmlLayout directly in a Log4j Core 2 configuration file. * Those using the Log4j 1 configuration compatibility layer with org.apache.log4j.xml.XMLLayout specified as the layout class. Users are advised to upgrade to Apache Log4j 1-to-Log4j 2 bridge version 2.25.4, which corrects this issue. Note: The Apache Log4j 1-to-Log4j 2 bridge is deprecated and will not be present in Log4j 3. Users are encouraged to consult the Log4j 1 to Log4j 2 migration guide https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html , and specifically the section on eliminating reliance on the bridge.",
    "evidence": "osv:DEBIAN-CVE-2026-34479",
    "products": [
      {
        "name": {
          "value": "apache-log4j2",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.19.0-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.26.1-1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "apache-log4j2",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.19.0-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.26.1-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "apache-log4j2",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.19.0-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "2.26.1-1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2026-34479",
      "aliases": [
        "DEBIAN-CVE-2026-34479"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "apache-log4j2",
            "purl": "pkg:deb/debian/apache-log4j2?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "2.19.0-2",
            "2.26.1-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-34479.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "apache-log4j2",
            "purl": "pkg:deb/debian/apache-log4j2?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "versions": [
            "2.19.0-2",
            "2.26.1-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-34479.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "apache-log4j2",
            "purl": "pkg:deb/debian/apache-log4j2?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "2.19.0-2",
            "2.26.1-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-34479.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-27T10:01:05.967036782Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-34479"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-34479"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-34479",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 461343,
  "published_at": "2026-04-10T16:16:31.27+00:00"
}