Security advisory

{
  "id": "5c96a300500abed5443caa246f0762bf1673ebd77c6e6a95ccdd2305f45d10b8",
  "url": "https://osv.dev/vulnerability/CVE-2021-3405",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-3405",
    "summary": "A flaw was found in libebml before 1.4.2. A heap overflow bug exists in the implementation of EbmlString::ReadData and EbmlUnicodeString::ReadData in libebml.",
    "evidence": "osv:CVE-2021-3405",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-3405",
      "aliases": [
        "CVE-2021-3405"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/matroska-org/libebml",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "6c59e5e1ce0087e4465f6d3f479449d3f6bcb167"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:matroska:libebml:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.4.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "release-1.4.1",
            "release-1.4.0",
            "release-1.3.10",
            "release-1.3.9",
            "release-1.3.8",
            "release-1.3.7",
            "release-1.3.6",
            "release-1.3.5",
            "release-1.3.4",
            "release-1.3.3",
            "release-1.3.2",
            "release-1.3.1",
            "release-1.3.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-3405.json",
            "vanir_signatures": [
              {
                "id": "CVE-2021-3405-de8843e5",
                "digest": {
                  "threshold": 0.9,
                  "line_hashes": [
                    "48377290074949130495164895076365827608",
                    "316359439968302076612153081825500800864"
                  ]
                },
                "source": "https://github.com/matroska-org/libebml/commit/6c59e5e1ce0087e4465f6d3f479449d3f6bcb167",
                "target": {
                  "file": "src/EbmlVersion.cpp"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
              }
            ],
            "vanir_signatures_modified": "2026-10-20T14:23:26Z"
          }
        }
      ],
      "modified": "2026-10-20T14:23:26.782276280Z",
      "provider": "osv",
      "references": [
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JNHQI6MDOECJ2HT5GCLEX2DMJFEOWPW7/",
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UHIIMWZKHHELFF4NRDMOOCS3HKK3K4DF/",
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YY7R2JZRO5I6WS62KTJFTZGKYELVFTVB/",
        "https://lists.debian.org/debian-lts-announce/2021/04/msg00016.html",
        "https://security.gentoo.org/glsa/202208-21",
        "https://github.com/Matroska-Org/libebml/issues/74"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*"
            ],
            "vendor_product": "debian:debian_linux",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "9.0"
                  },
                  {
                    "last_affected": "9.0"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          },
          {
            "cpes": [
              "cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*",
              "cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*",
              "cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*"
            ],
            "vendor_product": "fedoraproject:fedora",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "32"
                  },
                  {
                    "last_affected": "32"
                  },
                  {
                    "introduced": "33"
                  },
                  {
                    "last_affected": "33"
                  },
                  {
                    "introduced": "34"
                  },
                  {
                    "last_affected": "34"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-3405",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 388862,
  "published_at": "2021-02-23T20:15:12.087+00:00"
}