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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2018-20340
• https://blog.inhq.net/posts/yubico-libu2f-host-vuln-part1/
• https://developers.yubico.com/libu2f-host/Release_Notes.html
• https://seclists.org/bugtraq/2019/Feb/23
• https://security.gentoo.org/glsa/202004-15
• https://www.debian.org/security/2019/dsa-4389
• https://www.yubico.com/support/security-advisories/ysa-2019-01/