CVE-2021-31924
6.8 · MEDIUMOverview
CVE-2021-31924 is a medium-severity vulnerability affecting yubico pam-u2f. It was published on May 26, 2021 and has a CVSS 3.1 base score of 6.8 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 6.8, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from yubico. Update pam-u2f to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| yubico | pam-u2f | >= 0, < 1.1.1 | Affected |
References
Frequently Asked Questions
What is CVE-2021-31924?
CVE-2021-31924 is a medium-severity vulnerability affecting yubico pam-u2f. It was published on May 26, 2021 and has a CVSS 3.1 base score of 6.8 (MEDIUM).
How severe is CVE-2021-31924?
This vulnerability has a CVSS 3.1 base score of 6.8, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-31924?
Check the references section for vendor advisories and patches from yubico. Update pam-u2f to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-31924?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-31924 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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