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TI-2026-33522 Aliases CVE-2026-45785GHSA-5qwm-7pvp-w988

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

Priority MEDIUM 61CWE-835Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-835.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00184 8th percentileScored 2026-11-07
Fix Fixed openmcdf (openmcdf): 3.1.4OpenMcdf (NuGet): 3.1.4

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
openmcdfopenmcdfbefore 3.1.43.1.4Patch availableCNA
—OpenMcdf (NuGet)before 3.1.43.1.4Patch availableGHSA-5qwm-7pvp-w988
  • openmcdf Vendoropenmcdf Affected before 3.1.4 Fixed in 3.1.4 Patch available CNA
  • OpenMcdf (NuGet) Vendor— Affected before 3.1.4 Fixed in 3.1.4 Patch available GHSA-5qwm-7pvp-w988

Remediation

  • Fix · CNA openmcdf (openmcdf) Fixed in 3.1.4
  • Fix · GHSA-5qwm-7pvp-w988 OpenMcdf (NuGet) Fixed in 3.1.4 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-45785
  2. 2026-10-03 Alias added: GHSA-5qwm-7pvp-w988

References

Other 4

  • TI-2026-30094 OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle CVSS 3.1MEDIUM 6.2

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences