{
  "affected": [
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "OpenMcdf"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-41511"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-22T22:09:01Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\nOpenMcdf does not detect cycles in the directory entry red-black tree of a Compound File Binary (CFB) document. A crafted CFB file with a cycle in the `LeftSiblingID` / `RightSiblingID` chain causes `Storage.EnumerateEntries()` and `Storage.OpenStream()` to loop indefinitely, consuming the calling thread with no possibility of recovery via `try/catch`.\n\n### Details\nCFB directory entries form a red-black tree linked by `LeftSiblingID` and `RightSiblingID` fields. OpenMcdf\u0027s `DirectoryTreeEnumerator` and `DirectoryTree.TryGetDirectoryEntry` traverse this tree without tracking visited node IDs, so a crafted cycle (e.g. entry A\u0027s `RightSiblingID` points to entry B, and entry B\u0027s `LeftSiblingID` points back to entry A) causes traversal to loop indefinitely.\n\nTwo distinct code paths are affected:\n\n- **`Storage.EnumerateEntries()`** - `DirectoryTreeEnumerator.MoveNext()` never returns `false`; the same entry is yielded on every iteration and the caller\u0027s `foreach` never exits. Heap grows unboundedly as entries accumulate.\n- **`Storage.OpenStream()`** - `DirectoryTree.TryGetDirectoryEntry` loops indefinitely inside `DirectoryEntries.TryGetSibling` during the name lookup.\n\n### PoC\nA crafted CFB file with a sibling cycle (see attached) triggers the issue with the following code:\n\n```csharp\nusing OpenMcdf;\n\nusing var ms = new MemoryStream(File.ReadAllBytes(\"crafted.cfb\"));\nusing var root = RootStorage.Open(ms);\n\n// Never returns - EnumerateEntries loops indefinitely\nforeach (var entry in root.EnumerateEntries())\n{\n    Console.WriteLine(entry.Name);\n\n    if (entry.Type == EntryType.Stream)\n        root.OpenStream(entry.Name); // also hangs depending on the cycle structure\n}\n```\n\n### Impact\nA denial of service affecting any application that opens untrusted CFB files with OpenMcdf. A small crafted input carrying a valid CFB magic header (`D0 CF 11 E0 A1 B1 1A E1`) is sufficient to pass initial format validation and reach the vulnerable traversal code. No exception is thrown, so `try/catch` cannot protect callers. The affected thread is unrecoverable without killing the process.",
  "id": "GHSA-jxpf-xq2m-q525",
  "modified": "2026-04-22T22:09:01Z",
  "published": "2026-04-22T22:09:01Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/openmcdf/openmcdf/security/advisories/GHSA-jxpf-xq2m-q525"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openmcdf/openmcdf/commit/24f445a557fc4f46461cf6d02d296cce16c293a0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/openmcdf/openmcdf"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openmcdf/openmcdf/releases/tag/v3.1.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle"
}