{"id":"CVE-2026-41511","aliases":["EUVD-2026-28813","GHSA-jxpf-xq2m-q525"],"status":"published","title":"OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle","description":"OpenMcdf is a fully .NET / C# library to manipulate Compound File Binary File Format files, also known as Structured Storage. Prior to version 3.1.3, OpenMcdf 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. This issue has been patched in version 3.1.3.","severity":{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00187,"percentile":0.08377,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-835"],"published":"2026-04-22T22:09:01Z","modified":"2026-10-28T02:31:10Z","fixes":[{"ecosystem":"NuGet","package":"OpenMcdf","fixed_in":["3.1.3"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"NuGet","package":"OpenMcdf","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.3"}]}]},{"source":"osv","ecosystem":"NuGet","package":"OpenMcdf","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.3"}]}],"versions":["1.5.4","1.5.4.1","1.5.4.22637","2.0.5739","2.0.5739.40493","2.1.0.33051","2.1.2.1274","2.1.3.34720","2.1.3.34730","2.1.4.23498","2.1.5.22659","2.1.6.28924","2.2.0.1","2.2.1.12","2.2.1.2","2.2.1.3","2.2.1.4","2.2.1.5","2.2.1.6","2.2.1.8","2.2.1.9","2.3.0","2.3.1","2.4.0","2.4.1","3.0.0","3.0.0-preview1","3.0.1","3.0.2","3.0.3","3.1.0","3.1.1","3.1.2"]}],"products":[{"vendor":"ironfede","product":"openmcdf"},{"vendor":"openmcdf","product":"openmcdf"}],"references":[{"url":"https://github.com/openmcdf/openmcdf/security/advisories/GHSA-jxpf-xq2m-q525","tags":["x_refsource_CONFIRM","exploit","Exploit","Vendor Advisory","advisory","web"]},{"url":"https://github.com/openmcdf/openmcdf/commit/24f445a557fc4f46461cf6d02d296cce16c293a0","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://github.com/openmcdf/openmcdf/releases/tag/v3.1.3","tags":["x_refsource_MISC","Release Notes","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-41511","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-jxpf-xq2m-q525"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41511.json","tags":["advisory"]},{"url":"https://github.com/openmcdf/openmcdf","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-41511","title":"OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle","description":"OpenMcdf is a fully .NET / C# library to manipulate Compound File Binary File Format files, also known as Structured Storage. Prior to version 3.1.3, OpenMcdf 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. This issue has been patched in version 3.1.3.","status":"published","published":"2026-05-08T18:52:39.438Z","modified":"2026-05-11T18:45:06.128Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T13:41:08.498858Z"}],"euvd":[{"id":"EUVD-2026-28813","description":"OpenMcdf is a fully .NET / C# library to manipulate Compound File Binary File Format files, also known as Structured Storage. Prior to version 3.1.3, OpenMcdf 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. This issue has been patched in version 3.1.3.","status":"published","published":"2026-05-08T18:52:39Z","modified":"2026-05-11T18:45:06Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T19:05:10.375554Z"}],"ghsa":[{"id":"GHSA-jxpf-xq2m-q525","title":"OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle","description":"### 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's `DirectoryTreeEnumerator` and `DirectoryTree.TryGetDirectoryEntry` traverse this tree without tracking visited node IDs, so a crafted cycle (e.g. entry A's `RightSiblingID` points to entry B, and entry B's `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's `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.","status":"published","published":"2026-04-22T22:09:01Z","modified":"2026-05-13T13:33:53Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:40:07.01746Z"}],"nvd":[{"id":"CVE-2026-41511","description":"OpenMcdf is a fully .NET / C# library to manipulate Compound File Binary File Format files, also known as Structured Storage. Prior to version 3.1.3, OpenMcdf 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. This issue has been patched in version 3.1.3.","status":"published","published":"2026-05-08T19:16:31.363Z","modified":"2026-10-26T18:10:00.173Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:12:17.842772Z"}],"osv":[{"id":"CVE-2026-41511","title":"OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle","description":"OpenMcdf is a fully .NET / C# library to manipulate Compound File Binary File Format files, also known as Structured Storage. Prior to version 3.1.3, OpenMcdf 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. This issue has been patched in version 3.1.3.","status":"published","published":"2026-05-08T18:52:39.438Z","modified":"2026-10-28T02:31:10.233802596Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T15:45:03.764807Z"},{"id":"GHSA-jxpf-xq2m-q525","title":"OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle","description":"### 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's `DirectoryTreeEnumerator` and `DirectoryTree.TryGetDirectoryEntry` traverse this tree without tracking visited node IDs, so a crafted cycle (e.g. entry A's `RightSiblingID` points to entry B, and entry B's `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's `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.","status":"published","published":"2026-04-22T22:09:01Z","modified":"2026-05-13T13:52:34.912355Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T15:46:51.10002Z"}]}}