CVE-2021-31924
Description
Yubico pam-u2f before 1.1.1 has a logic issue that, depending on the pam-u2f configuration and the application used, could lead to a local PIN bypass. This issue does not allow user presence (touch) or cryptographic signature verification to be bypassed, so an attacker would still need to physically possess and interact with the YubiKey or another enrolled authenticator. If pam-u2f is configured to require PIN authentication, and the application using pam-u2f allows the user to submit NULL as the PIN, pam-u2f will attempt to perform a FIDO2 authentication without PIN. If this authentication is successful, the PIN requirement is bypassed.
CVSS Details
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Threat Intelligence
No active exploitation signals — not in CISA KEV and no EPSS score yet.
Weaknesses 1
Affected Products 3
| Vendor | Product | Version | Range |
|---|---|---|---|
| yubico | pam-u2f | * | <1.1.1 |
| fedoraproject | fedora | 34 | any |
| fedoraproject | fedora | 35 | any |
References 5
- developers.yubico.com https://developers.yubico.com/pam-u2f/
- lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CRBVOZEMVO72FV4Z5O4GBGSURXHWRGD3/
- lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IL3I5AKECLMK4ADLLACLOEF7H5CMNDP2/
- security.gentoo.org https://security.gentoo.org/glsa/202208-11
- yubico.com https://www.yubico.com/support/security-advisories/ysa-2021-03
Remediation
No remediation data recorded yet
Check vendor advisories and the NVD entry for patch availability.