# 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.

- **Severity:** Medium 6.2 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 May 2026
- **Updated:** 11 May 2026
- **Also known as:** GHSA-jxpf-xq2m-q525

## 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 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-41511?

2 open source packages ship an affected version, including OpenMcdf. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `OpenMcdf` | NuGet | All versions | 3.1.3 |
| `OpenMcdf` | NuGet | All versions | 3.1.3 |

Products: Openmcdf Openmcdf.

## How do I fix CVE-2026-41511?

Upgrade OpenMcdf to 3.1.3 or later.

## Is CVE-2026-41511 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41511 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-41511 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41511 exists.

Affected packages and fixed versions:
- OpenMcdf (NuGet): affected all versions; fixed in 3.1.3
- OpenMcdf (NuGet): affected all versions; fixed in 3.1.3

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-41511/ (Markdown: https://insights.sbomify.com/CVE-2026-41511/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-41511
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-41511
- OSV: https://osv.dev/vulnerability/CVE-2026-41511

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-41511/
Summaries are generated and may contain mistakes; the official description above is the record.