CVE-2026-48982
pam_usb: Missing O_EXCL on pad temp file creation allows concurrent update race
Description
pam_usb provides hardware authentication for Linux using ordinary removable media. In versions prior to 0.9.2, when updating a one-time pad file, a temporary file is created using open() without the O_EXCL flag. Without O_EXCL, the create operation is not atomic: two concurrent processes racing to update the same pad may both succeed in opening the file, with the second write silently overwriting the first. The one-time pad is the core replay-prevention mechanism of pam_usb. A successful race could result in the stored pad value diverging from what either process expected, potentially causing authentication failures or, in a precisely timed attack, creating a window for pad reuse. This issue has been fixed in version 0.9.2.
INFO
Published Date :
June 18, 2026, 8:16 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 | [email protected] |
Solution
- Update pam_usb to version 0.9.2 or later.
- Ensure file creation uses the O_EXCL flag.
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-2026-48982.
| URL | Resource |
|---|---|
| https://github.com/mcdope/pam_usb/releases/tag/0.9.2 | |
| https://github.com/mcdope/pam_usb/security/advisories/GHSA-hxh6-9574-5vp6 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-48982 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-2026-48982
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-2026-48982 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-48982 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 versiones anteriores a la 0.9.2, al actualizar un archivo de pad de un solo uso, se crea un archivo temporal utilizando open() sin la bandera O_EXCL. Sin O_EXCL, la operación de creación no es atómica: dos procesos concurrentes compitiendo por actualizar el mismo pad pueden ambos lograr abrir el archivo, con la segunda escritura sobrescribiendo silenciosamente la primera. El pad de un solo uso es el mecanismo central de prevención de repeticiones de pam_usb. Una carrera exitosa podría resultar en que el valor del pad almacenado diverja de lo que cualquiera de los procesos esperaba, lo que podría causar fallos de autenticación o, en un ataque precisamente sincronizado, crear una ventana para la reutilización del pad. Este problema ha sido solucionado en la versión 0.9.2. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 22, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-48982', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-22T15:35:08.355851Z'} -
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 prior to 0.9.2, when updating a one-time pad file, a temporary file is created using open() without the O_EXCL flag. Without O_EXCL, the create operation is not atomic: two concurrent processes racing to update the same pad may both succeed in opening the file, with the second write silently overwriting the first. The one-time pad is the core replay-prevention mechanism of pam_usb. A successful race could result in the stored pad value diverging from what either process expected, potentially causing authentication failures or, in a precisely timed attack, creating a window for pad reuse. This issue has been fixed in version 0.9.2. Added CVSS V3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L Added CWE CWE-362 Added Reference https://github.com/mcdope/pam_usb/releases/tag/0.9.2 Added Reference https://github.com/mcdope/pam_usb/security/advisories/GHSA-hxh6-9574-5vp6