# CVE-2026-40947: Other in libfido2

> An attacker can execute arbitrary code via DLL hijacking due to an unintended search path in Yubico FIDO2 libraries.

- **Severity:** Low 2.9 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Apr 2026
- **Updated:** 16 Apr 2026
- **Also known as:** GHSA-6vgr-gf7r-f3jc

## What is CVE-2026-40947?

CVE-2026-40947 is a low-severity vulnerability in Yubico libfido2, published on 15 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Yubico libfido2 before 1.17.0, python-fido2 before 2.2.0, and yubikey-manager before 5.9.1 have an unintended DLL search path.

Weakness: CWE-426 (Untrusted Search Path)

## Which versions are affected by CVE-2026-40947?


## How do I fix CVE-2026-40947?

No fix has been published for CVE-2026-40947 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40947 being exploited?

There is no known exploitation of CVE-2026-40947 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40947 and fix it if it is affected.

What it is: CVE-2026-40947 is a low-severity vulnerability in Yubico libfido2, published on 15 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-40947 in the wild and no public exploit code.

Affected product: Yubico libfido2. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-40947/ (Markdown: https://insights.sbomify.com/CVE-2026-40947/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40947
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40947
- OSV: https://osv.dev/vulnerability/CVE-2026-40947

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-40947/
Summaries are generated and may contain mistakes; the official description above is the record.