CVE-2021-31924

Severity Score

6.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

Yubico pam-u2f antes de la versión 1.1.1 tiene un problema lógico que, dependiendo de la configuración de pam-u2f y de la aplicación utilizada, podría conducir a una derivación local del PIN. Este problema no permite eludir la presencia del usuario (tacto) o la verificación de la firma criptográfica, por lo que un atacante todavía tendría que poseer físicamente e interactuar con la YubiKey u otro autenticador inscrito. Si pam-u2f está configurado para requerir la autenticación con PIN, y la aplicación que utiliza pam-u2f permite al usuario enviar NULL como PIN, pam-u2f intentará realizar una autenticación FIDO2 sin PIN. Si esta autenticación tiene éxito, el requisito del PIN se omite

*Credits: N/A

Attack Vector

Physical

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-04-30 CVE Reserved
2021-05-25 CVE Published
2024-02-08 EPSS Updated
2024-08-03 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-287: Improper Authentication

CAPEC

References (5)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC
https://developers.yubico.com/pam-u2f	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CRBVOZEMVO72FV4Z5O4GBGSURXHWRGD3	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IL3I5AKECLMK4ADLLACLOEF7H5CMNDP2	2023-11-07
https://security.gentoo.org/glsa/202208-11	2023-11-07
https://www.yubico.com/support/security-advisories/ysa-2021-03	2023-11-07

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Yubico Search vendor "Yubico"		Pam-u2f Search vendor "Yubico" for product "Pam-u2f"				< 1.1.1 Search vendor "Yubico" for product "Pam-u2f" and version " < 1.1.1"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				34 Search vendor "Fedoraproject" for product "Fedora" and version "34"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				35 Search vendor "Fedoraproject" for product "Fedora" and version "35"		-		Affected