Bug 2028244 (CVE-2021-31924) - CVE-2021-31924 pam-u2f: Logic issue may lead to local PIN bypass
Summary: CVE-2021-31924 pam-u2f: Logic issue may lead to local PIN bypass
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2021-31924
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2028245
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-12-01 19:17 UTC by Pedro Sampaio
Modified: 2021-12-01 19:38 UTC (History)
3 users (show)

Fixed In Version:
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Clone Of:
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Last Closed: 2021-12-01 19:38:44 UTC


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Description Pedro Sampaio 2021-12-01 19:17:45 UTC
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.

References:

https://www.yubico.com/support/security-advisories/ysa-2021-03
https://developers.yubico.com/pam-u2f/

Comment 1 Pedro Sampaio 2021-12-01 19:18:00 UTC
Created pam-u2f tracking bugs for this issue:

Affects: fedora-all [bug 2028245]

Comment 2 Product Security DevOps Team 2021-12-01 19:38:43 UTC
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.


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