---
cve: "CVE-2026-47270"
severity: "MEDIUM"
cvss: 6.3
epss: "11%"
vendor: "mcdope"
kev: false
exploited: false
published: "2026-05-27 21:16:18"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-18T05:11:06+02:00"
---

# CVE-2026-47270

> 6.3 MEDIUM · 🧪 PoC

## Beschreibung

pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0, pam_usb is a PAM module loaded into the host process (sudo, login, GDM, GNOME Shell). Display managers such as GDM run multiple concurrent authentication threads. Three functions used by the deny_remote feature called the non-reentrant strtok(), which stores state in a single global pointer. If two authentications race, one thread's strtok() call can overwrite the other's in-progress tokenisation pointer, causing incorrect parsing of the tmux session data or the /proc environ scan that backs the remote-session detection logic. Additionally, pusb_tmux_get_client_tty() passed the raw pointer returned by getenv(TMUX) directly to strtok(). getenv() returns a pointer into the live process environment block; strtok() inserts NUL bytes into that block, permanently corrupting the TMUX variable for subsequent code running in the same process. In long-lived display managers this affects all future authentications in that process. The combined effect can cause deny_remote=true to return an incorrect decision for a remote session, or an incorrect decision for a local session, depending on thread interleaving. This vulnerability is fixed in 0.9.0.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- 94f1640a61d49dfaf38e782680a52f01d5bf8b51 (Commit)
- d003e551b794a9e3774ff4720830fb7aadaa48bd (Commit)

## Referenzen

- <https://github.com/mcdope/pam_usb/security/advisories/GHSA-j3xw-vc43-x7jg>
- <https://github.com/mcdope/pam_usb/commit/94f1640a61d49dfaf38e782680a52f01d5bf8b51>
- <https://github.com/mcdope/pam_usb/commit/d003e551b794a9e3774ff4720830fb7aadaa48bd>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-47270) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_