CVE-2026-48981
pam_usb: xmlReadFile flags=0 permits XXE network entity fetching in conf.c
Description
pam_usb provides hardware authentication for Linux using ordinary removable media. In versions prior to 0.9.2, pam_usb calls xmlReadFile() with flags=0 when loading the configuration file, allowing libxml2 to process external entity references (XXE), potentially making outbound network connections or local file reads at XML parse time from the context of the authenticating process. The vulnerability requires the configuration file to contain crafted XML entity references. Since pam_usb.conf is root-owned, direct exploitation requires prior write access to the config, but the defence-in-depth impact is significant given that pam_usb.so runs in setuid contexts (sudo, su). This issue has been fixed in version 0.9.2.
INFO
Published Date :
June 18, 2026, 6:55 p.m.
Last Modified :
June 18, 2026, 6:55 p.m.
Remotely Exploit :
No
Source :
GitHub_M
Affected Products
The following products are affected by CVE-2026-48981
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update pam_usb to version 0.9.2 or later.
- Review configuration files for malicious XML entities.
- Restrict write access to pam_usb.conf.
- Monitor processes running in setuid contexts.
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