VDB
CVE-2021-31924
CVE-2021-31924
REJECTED
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.
EPSS 0.09% · 25.4th percentile
Risk Scores
EPSS Score
0.09%
25.4th percentile
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Ubuntu:25.04 | pam-u2f | 0, 1.3.0-1, 1.3.2-1 |
| Ubuntu:Pro:20.04:LTS | pam-u2f | 0, 1.0.8-1 |
| Ubuntu:Pro:18.04:LTS | pam-u2f | 1.0.4-2, 0 |
| Ubuntu:Pro:16.04:LTS | pam-u2f | 0, 1.0.1-1, 1.0.2-1 |
| Ubuntu:22.04:LTS | pam-u2f | 0, 1.1.0-1.1build1, 1.1.0-1.1 |
| Ubuntu:24.04:LTS | pam-u2f | 1.1.0-1.1build3, 1.1.0-1.1build2, 1.1.0-1.1build1 |
Timeline
- May 25, 2021 CVE Published
- May 26, 2021 EPSS Score
- Jul 28, 2021 EPSS Score
- Sep 27, 2021 EPSS Score
- Jan 6, 2022 EPSS Score
- Jan 28, 2022 EPSS Score
- Feb 4, 2022 EPSS Score
- Mar 3, 2022 EPSS Score
- Mar 30, 2022 EPSS Score
- Apr 1, 2022 EPSS Score
- Jul 31, 2022 EPSS Score
- Oct 1, 2022 EPSS Score
References
- https://ubuntu.com/security/CVE-2021-31924 third-party-advisory
- https://www.yubico.com/support/security-advisories/ysa-2021-03 third-party-advisory
- https://developers.yubico.com/pam-u2f/ third-party-advisory
- https://www.cve.org/CVERecord?id=CVE-2021-31924 third-party-advisory