Vulnerability-Lookup

CVE-2026-41511 (GCVE-0-2026-41511)

Vulnerability from cvelistv5 – Published: 2026-05-08 18:52 – Updated: 2026-05-11 18:45

Title

OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle

Summary

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

6.2 (Medium)


                        
                          CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE

CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/openmcdf/openmcdf/security/adv…	x_refsource_CONFIRM
https://github.com/openmcdf/openmcdf/commit/24f44…	x_refsource_MISC
https://github.com/openmcdf/openmcdf/releases/tag…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
ironfede	openmcdf	Affected: < 3.1.3

Show details on NVD website

JSON

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FKIE_CVE-2026-41511

Vulnerability from fkie_nvd - Published: 2026-05-08 19:16 - Updated: 2026-05-13 17:26

Severity

6.2 (Medium) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/openmcdf/openmcdf/commit/24f445a557fc4f46461cf6d02d296cce16c293a0
	security-advisories@github.com	https://github.com/openmcdf/openmcdf/releases/tag/v3.1.3
	security-advisories@github.com	https://github.com/openmcdf/openmcdf/security/advisories/GHSA-jxpf-xq2m-q525
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/openmcdf/openmcdf/security/advisories/GHSA-jxpf-xq2m-q525

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "id": "CVE-2026-41511",
  "lastModified": "2026-05-13T17:26:28.013",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 6.2,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
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        "exploitabilityScore": 2.5,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
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  "published": "2026-05-08T19:16:31.363",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/openmcdf/openmcdf/commit/24f445a557fc4f46461cf6d02d296cce16c293a0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/openmcdf/openmcdf/releases/tag/v3.1.3"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/openmcdf/openmcdf/security/advisories/GHSA-jxpf-xq2m-q525"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/openmcdf/openmcdf/security/advisories/GHSA-jxpf-xq2m-q525"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-835"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-JXPF-XQ2M-Q525

Vulnerability from github – Published: 2026-04-22 22:09 – Updated: 2026-05-13 13:33

Summary

OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle

Details

Summary

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.

Details

CFB 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.

Two distinct code paths are affected:

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.
Storage.OpenStream() - DirectoryTree.TryGetDirectoryEntry loops indefinitely inside DirectoryEntries.TryGetSibling during the name lookup.

PoC

A crafted CFB file with a sibling cycle (see attached) triggers the issue with the following code:

using OpenMcdf;

using var ms = new MemoryStream(File.ReadAllBytes("crafted.cfb"));
using var root = RootStorage.Open(ms);

// Never returns - EnumerateEntries loops indefinitely
foreach (var entry in root.EnumerateEntries())
{
    Console.WriteLine(entry.Name);

    if (entry.Type == EntryType.Stream)
        root.OpenStream(entry.Name); // also hangs depending on the cycle structure
}

Impact

A 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.

Severity

6.2 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Show details on source website

JSON

To clipboard

{
  "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": "2026-05-08T19:16:31Z",
    "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": "2026-05-13T13:33:51Z",
  "published": "2026-04-22T22:09:01Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/openmcdf/openmcdf/security/advisories/GHSA-jxpf-xq2m-q525"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41511"
    },
    {
      "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"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-41511 (GCVE-0-2026-41511)

FKIE_CVE-2026-41511

GHSA-JXPF-XQ2M-Q525

Summary

Details

PoC

Impact

Tags

Sightings

Nomenclature