CVE-2026-41511

OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle

MEDIUM
5.5
CVSS Score
Published: May 8, 2026 at 06:52 PM UTC
Updated: October 26, 2026 at 06:10 PM UTC
2 products affected across 2 vendorsOpenmcdfOpenmcdf

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.2%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.1.3
Affected range stops below 3.1.3, so it looks safe — our inference, not a vendor statement
v < 3.1.3
Affected range stops below 3.1.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-835

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