CVE-2026-45785

OpenMcdf: Uncatchable infinite loop in DirectoryTree.TryGetDirectoryEntry on crafted CFB directory cycle

Published Jul 17, 2026 CVSS 3.1 · 6.2 Medium EPSS < 1% KEV · Not listed
Description
OpenMcdf is a fully .NET / C# library to manipulate Compound File Binary File Format files, also known as Structured Storage. In 3.1.3 and earlier, the BST name-lookup loop in DirectoryTree.TryGetDirectoryEntry (OpenMcdf/DirectoryTree.cs:35-46) walks directory entries by repeatedly calling directories.TryGetSibling(child, siblingType, validateColor). A crafted CFB file with cyclic Left/Right sibling links among directory entries, constructed so the per-step BST-order check in TryGetSibling (DirectoryEntries.cs:84-85) is satisfied at every step, drives this while (child is not null) loop forever. There is no cycle detection in TryGetDirectoryEntry, and the bug is reachable from RootStorage.OpenStorage(name), TryOpenStorage(name), OpenStream(name), and TryOpenStream(name), causing an unrecoverable denial of service. This issue is fixed in version 3.1.4.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-5qwm-7pvp-w988 OpenMcdf: Uncatchable infinite loop in DirectoryTree.TryGetDirectoryEntry on crafted CFB directory cycle
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Openmcdf
Openmcdf openmcdf
Vendors & Products Openmcdf
Openmcdf openmcdf
Type Values Removed Values Added
Description OpenMcdf is a fully .NET / C# library to manipulate Compound File Binary File Format files, also known as Structured Storage. In 3.1.3 and earlier, the BST name-lookup loop in DirectoryTree.TryGetDirectoryEntry (OpenMcdf/DirectoryTree.cs:35-46) walks directory entries by repeatedly calling directories.TryGetSibling(child, siblingType, validateColor). A crafted CFB file with cyclic Left/Right sibling links among directory entries, constructed so the per-step BST-order check in TryGetSibling (DirectoryEntries.cs:84-85) is satisfied at every step, drives this while (child is not null) loop forever. There is no cycle detection in TryGetDirectoryEntry, and the bug is reachable from RootStorage.OpenStorage(name), TryOpenStorage(name), OpenStream(name), and TryOpenStream(name), causing an unrecoverable denial of service. This issue is fixed in version 3.1.4.
Title OpenMcdf: Uncatchable infinite loop in DirectoryTree.TryGetDirectoryEntry on crafted CFB directory cycle
Weaknesses CWE-835
References
Metrics cvssV3_1

{'score': 6.2, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 21, 2026, 2:20 AM
Reserved
May 13, 2026, 7:45 AM
Status
Deferred
Published
Jul 17, 2026, 9:17 PM
Modified
Jul 23, 2026, 6:12 PM