CVE-2026-47270

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering.

Exploit odds

0.1% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-27 21:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-26 12:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.1% in the next 30 days (EPSS).
• Severity: 6.3 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-05-27 21:16 UTC

Last modified

2026-10-26 12:10 UTC

Exploit probability

0.1% · EPSS, next 30 days

Weakness

CWE-362 · Race condition

Record status

Deferred

Attack profile CVSS 3.1 · 6.3

Attack vector

Local

Complexity

High

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-47270.md and follow it. Check whether this project is affected by CVE-2026-47270. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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