Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M
CVE-2026-45785OpenMcdf: Uncatchable infinite loop in DirectoryTree.TryGetDirectoryEntry on crafted CFB directory cycle
Medium 6.2
In plain English
A medium-severity infinite loop in openmcdf from openmcdf. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| NuGet | openmcdf | 3.1.4 | GHSA-5qwm-7pvp-w988 |
Affected products (as reported)
Weakness: CWE-835 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/openmcdf/openmcdf/security/advisories/GHSA-5qwm-7pvp-w988 x_refsource_CONFIRM
- https://github.com/openmcdf/openmcdf/commit/c6f82db722bd85db7b0caed3ca1aa374f1e07bc7 x_refsource_MISC
- https://github.com/openmcdf/openmcdf/releases/tag/v3.1.4 x_refsource_MISC