CVE-2026-48985
pam_usb: NULL Dereference Crash in pusb_is_loginctl_local when loginctl Returns Empty Remote Field
Description
pam_usb provides hardware authentication for Linux using ordinary removable media. In versions 0.9.1 and below, pusb_is_loginctl_local() can cause a NULL dereference crash when parsing loginctl output. The function calls popen() and reads the result; if the Remote field is only a newline, fgets() succeeds but strtok_r(buf, "\n", &saveptr) returns NULL. A subsequent strcmp(is_remote, "no") then dereferences NULL, causing undefined behavior (typically SIGSEGV) and crashing the PAM module. This can crash the authenticating process (e.g., sudo, login) and, depending on PAM stack configuration, deny access for all users of the affected service. This issue has been fixed in version 0.9.2.
INFO
Published Date :
June 18, 2026, 6:16 p.m.
Last Modified :
Oct. 26, 2026, 11:10 a.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update pam_usb to version 0.9.2 or later.
- Restart the affected PAM module.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-48985.
| URL | Resource |
|---|---|
| https://github.com/mcdope/pam_usb/releases/tag/0.9.2 | |
| https://github.com/mcdope/pam_usb/security/advisories/GHSA-7j6h-wfc2-mg5q |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-48985 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-48985
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-48985 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-48985 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 26, 2026
Action Type Old Value New Value Added Translation Title: pam_usb de mcdope, Description: pam_usb proporciona autenticación de hardware para Linux utilizando medios extraíbles ordinarios. En las versiones 0.9.1 e inferiores, pusb_is_loginctl_local() puede causar un fallo por desreferencia de NULL al analizar la salida de loginctl. La función llama a popen() y lee el resultado; si el campo Remote es solo un salto de línea, fgets() tiene éxito pero strtok_r(buf, “\n”, &saveptr) devuelve NULL. Un posterior strcmp(is_remote, “no”) entonces desreferencia NULL, causando un comportamiento indefinido (típicamente SIGSEGV) y bloqueando el módulo PAM. Esto puede bloquear el proceso de autenticación (p. ej., sudo, login) y, dependiendo de la configuración de la pila PAM, denegar el acceso a todos los usuarios del servicio afectado. Este problema ha sido solucionado en la versión 0.9.2. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 18, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-48985', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-18T19:08:54.015120Z'} -
New CVE Received by [email protected]
Jun. 18, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'mcdope', 'product': 'pam_usb', 'versions': [{'status': 'affected', 'version': '< 0.9.2'}]}] Added Description pam_usb provides hardware authentication for Linux using ordinary removable media. In versions 0.9.1 and below, pusb_is_loginctl_local() can cause a NULL dereference crash when parsing loginctl output. The function calls popen() and reads the result; if the Remote field is only a newline, fgets() succeeds but strtok_r(buf, "\n", &saveptr) returns NULL. A subsequent strcmp(is_remote, "no") then dereferences NULL, causing undefined behavior (typically SIGSEGV) and crashing the PAM module. This can crash the authenticating process (e.g., sudo, login) and, depending on PAM stack configuration, deny access for all users of the affected service. This issue has been fixed in version 0.9.2. Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-476 Added Reference https://github.com/mcdope/pam_usb/releases/tag/0.9.2 Added Reference https://github.com/mcdope/pam_usb/security/advisories/GHSA-7j6h-wfc2-mg5q