CVE-2026-41511 OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle
A crafted CFB file causes an infinite loop in OpenMcdf, leading to denial of service by consuming the calling thread.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-41511?
CVE-2026-41511 is a medium-severity denial of service vulnerability in ironfede openmcdf, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-835
Which versions are affected by CVE-2026-41511?
2 open source packages ship an affected version, including OpenMcdf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
OpenMcdf NuGet | All versions | 3.1.3 |
OpenMcdf NuGet | All versions | 3.1.3 |
Products include Openmcdf Openmcdf.
How do I fix CVE-2026-41511?
Upgrade OpenMcdf to 3.1.3 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-41511 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41511 exists.
Sources
Also known as GHSA-jxpf-xq2m-q525.