Vulnerability Details : CVE-2021-31924
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.
Vulnerability category: BypassGain privilege
Products affected by CVE-2021-31924
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
- cpe:2.3:a:yubico:pam-u2f:*:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2021-31924
0.12%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 47 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2021-31924
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
---|---|---|---|---|---|---|
4.6
|
MEDIUM | AV:L/AC:L/Au:N/C:P/I:P/A:P |
3.9
|
6.4
|
NIST | |
6.8
|
MEDIUM | CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
0.9
|
5.9
|
NIST |
CWE ids for CVE-2021-31924
-
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.Assigned by: nvd@nist.gov (Primary)
References for CVE-2021-31924
-
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/IL3I5AKECLMK4ADLLACLOEF7H5CMNDP2/
[SECURITY] Fedora 34 Update: pam-u2f-1.2.0-2.fc34 - package-announce - Fedora Mailing-ListsMailing List;Third Party Advisory
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https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/CRBVOZEMVO72FV4Z5O4GBGSURXHWRGD3/
[SECURITY] Fedora 35 Update: pam-u2f-1.2.0-2.fc35 - package-announce - Fedora Mailing-ListsMailing List;Third Party Advisory
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https://www.yubico.com/support/security-advisories/ysa-2021-03
Security Advisory YSA-2021-03 - YubicoVendor Advisory
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https://security.gentoo.org/glsa/202208-11
Yubico pam-u2f: Local PIN Bypass vulnerability (GLSA 202208-11) — Gentoo securityThird Party Advisory
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https://developers.yubico.com/pam-u2f/
pam-u2fProduct;Vendor Advisory
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