Bad-cast to std::__shared_weak_count from invalid vptr

{
  "id": "7054fa0b0625608c81b1387395ea71d62e55852b2e32dc9bcacc244e0652db4e",
  "url": "https://osv.dev/vulnerability/OSV-2026-867",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Bad-cast to std::__shared_weak_count from invalid vptr",
    "summary": "OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=520147546 ``` Crash type: Bad-cast Crash state: Bad-cast to std::__shared_weak_count from invalid vptr std::__1::shared_ptr::shared_ptr Assimp::STEP::ReadFileHeader ```",
    "evidence": "osv:OSV-2026-867",
    "products": [
      {
        "name": {
          "value": "assimp",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "OSV-2026-867",
      "aliases": [
        "OSV-2026-867"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/assimp/assimp.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "cac67afe479ac9be595d03bfa811d0e6a6baf39a"
                },
                {
                  "fixed": "d59e42da06d4e182845aa47dab5848269efd998d"
                }
              ]
            }
          ],
          "package": {
            "name": "assimp",
            "purl": "pkg:generic/assimp",
            "ecosystem": "OSS-Fuzz"
          },
          "database_specific": {
            "source": "https://github.com/google/oss-fuzz-vulns/blob/main/vulns/assimp/OSV-2026-867.yaml",
            "fixed_range": "c3f68d29c4237435652ec242e00928d5dd2b3011:d59e42da06d4e182845aa47dab5848269efd998d",
            "introduced_range": "be3d938e3e22d364b38807a247b3593fa7b260bd:626219cdd32f8fb0891464f27663d2667078d7cc"
          },
          "ecosystem_specific": {
            "severity": "HIGH"
          }
        }
      ],
      "modified": "2026-10-24T16:15:02.918052681Z",
      "provider": "osv",
      "references": [
        "https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=520147546"
      ]
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 443937,
  "published_at": "2026-06-07T00:02:11.977245+00:00"
}