Authentication Bypass Vulnerability in pam_usb for Linux
CVE-2026-47269

7.4HIGH

Key Information:

Vendor

Mcdope

Status
Pam Usb
Vendor
CVE Published:
27 May 2026

What is CVE-2026-47269?

The pam_usb module for Linux, designed for hardware authentication using removable media, has a vulnerability that enables authentication bypass over SSH. This issue arises when the deny_remote feature fails to accurately detect remote sessions due to incorrect address checking in the utmpx structure. Specifically, the vulnerability overlooks IPv4-mapped IPv6 addresses, which can be misinterpreted under certain system configurations, such as those commonly found in Ubuntu and Debian. As a result, an attacker with physical access to a USB device can authenticate remotely as if they were directly connected to the terminal, circumventing security measures intended to restrict remote access. This vulnerability has been addressed in version 0.9.0.

Affected Version(s)

pam_usb < 0.9.0

References

https://github.com/mcdope/pam_usb/security/advisories/GHS...
x_refsource_CONFIRM
https://github.com/mcdope/pam_usb/commit/804fe24eae3d742d...
x_refsource_MISC

CVSS V3.1

Score:
7.4
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.