---
cve: "CVE-2026-47269"
severity: "HIGH"
cvss: 7.4
epss: "31%"
vendor: "mcdope"
kev: false
exploited: false
published: "2026-05-27 21:16:18"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-15T21:09:11+02:00"
---

# CVE-2026-47269

> 7.4 HIGH · 🧪 PoC

## Beschreibung

pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0,  pam_usb's deny_remote feature checks utmpx ut_addr_v6 to detect whether an authentication request originates from a remote session. The outer guard was if (utent->ut_addr_v6[0] != 0), which only tests the first 32-bit word of the 128-bit address field. IPv4-mapped IPv6 addresses (::ffff:x.x.x.x) store the IPv4 address in ut_addr_v6[3] with ut_addr_v6[0] == 0. On systems where the SSH daemon listens on :: (IPv6 wildcard) with AddressFamily any -- common on Ubuntu and Debian -- incoming IPv4 connections are recorded in utmpx as IPv4-mapped IPv6 addresses. The outer check evaluates to false, the remote-detection block is skipped entirely, and the session is treated as local. deny_remote=true does not block the authentication. An attacker with physical access to a registered USB device can authenticate over SSH on an affected system as if they were sitting at a local terminal, bypassing the deny_remote restriction. This vulnerability is fixed in 0.9.0.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 804fe24eae3d742d8be05fd015e36abc3c7d94e5 (Commit)

## Referenzen

- <https://github.com/mcdope/pam_usb/security/advisories/GHSA-jmmj-qhrq-w45g>
- <https://github.com/mcdope/pam_usb/commit/804fe24eae3d742d8be05fd015e36abc3c7d94e5>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-47269) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_