# CVE-2026-48981: mcdope pam_usb XXE in configuration file parsing

Source: https://junglewise.ai/threats/cve-2026-48981-mcdope-pam-usb-xxe-in-configuration-file-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-18. Updated: 2026-06-21  
License: CC BY 4.0 with a link back

CVE-2026-48981 · Severity: medium · CVSS 6.7 · Published 2026-06-18

pam_usb is a tool that allows users to log into Linux systems using a USB drive instead of a password. A security flaw in how it reads its configuration file could allow an attacker who already has high-level access to the system to read sensitive local files or trigger unauthorized network connections. This is particularly serious because the software runs with elevated system privileges during the login process.

Technologies: [Mcdope Pam Usb](https://junglewise.ai/threats/technologies/pam-usb). Vendors: [Mcdope](https://junglewise.ai/threats/vendors/mcdope).

## Quick answers

**Is CVE-2026-48981 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48981 being exploited in the wild.

**How severe is CVE-2026-48981?** Medium severity, with a CVSS score of 6.7, published 18 June 2026.

**Which products and versions are affected?** Mcdope Pam Usb < 0.9.2.

**Is there a fix for CVE-2026-48981?** A patch was published on 2023-05-23: Version 0.9.2 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-48981 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-48981?** Check whether you run Mcdope Pam Usb at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The pam_usb module fails to disable external entity expansion when calling libxml2's xmlReadFile() function, using flags=0. This leads to an XML External Entity (XXE) vulnerability. An attacker with write access to the root-owned pam_usb.conf can insert malicious entity references. Because pam_usb.so is executed within privileged setuid contexts (such as sudo or su), this allows for the reading of sensitive local files or the initiation of outbound network requests from a highly privileged process. The issue is resolved in version 0.9.2 by passing explicit parser flags to block external entity expansion.

## Affected products

- mcdope pam_usb < 0.9.2

## Timeline

- 2023-05-23: patched: Version 0.9.2 released
- 2026-05-24: advisory: GitHub Security Advisory published
- 2026-06-18: disclosed: CVE-2026-48981 published to NVD

## References

- [https://github.com/mcdope/pam_usb/releases/tag/0.9.2](https://github.com/mcdope/pam_usb/releases/tag/0.9.2)
- [https://github.com/mcdope/pam_usb/security/advisories/GHSA-96vv-r4wc-28c2](https://github.com/mcdope/pam_usb/security/advisories/GHSA-96vv-r4wc-28c2)

## Related threats

- [pam_usb heap out-of-bounds read in display server handling](https://junglewise.ai/threats/cve-2026-64667-pam-usb-provides-hardware-authentication-for-linux-using)
- [pam_usb XRDP session bypass via environment variable](https://junglewise.ai/threats/cve-2026-64666-pam-usb-provides-hardware-authentication-for-linux-using)
- [mcdope pam_usb symlink race condition in pad directory creation](https://junglewise.ai/threats/cve-2026-48983-mcdope-pam-usb-symlink-race-condition-in-pad-directory-creation)
- [mcdope pam_usb race condition in one-time pad update](https://junglewise.ai/threats/cve-2026-48982-mcdope-pam-usb-race-condition-in-one-time-pad-update)
- [mcdope pam_usb environment variable injection in local-check logic](https://junglewise.ai/threats/cve-2026-48980-mcdope-pam-usb-environment-variable-injection-in-local-check)