pam_usb: getenv() used in PAM context allows environment variable injection into local-check logic

published 2026-06-18 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-37937

cvss: 6.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits: 0; none known

pam_usb provides hardware authentication for Linux using removable media. In versions prior to 0.9.2, getenv() environment variables XRDP_SESSION, DISPLAY and TMUX allow environment variable injection into local-check logic. These environment variables influence whether a current session is local or remote, and a PAM module that runs in the context of setuid binaries (sudo, su), getenv() returns attacker-controlled values whenever the process environment has been manipulated by a local user. This issue has been fixed in version 0.9.2.

Patch / fix

links 1

github.com/mcdope/pam_usb/releases/tag/0.9.2 release

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 4 mo ago (2026-06-18)

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.3	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected products

mcdope pam_usb

Classification

Weakness

CWE-454 External Initialization of Trusted Variables or Data Stores
CWE-807 Reliance on Untrusted Inputs in a Security Decision

References

Sources

CVE List CVE-2026-48980
NVD CVE-2026-48980

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary