CVE-2026-48981 (GCVE-0-2026-48981)

Vulnerability from cvelistv5 – Published: 2026-06-18 18:55 – Updated: 2026-06-22 15:19
VLAI
Title
pam_usb: xmlReadFile flags=0 permits XXE network entity fetching in conf.c
Summary
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.
Severity
6.7 (Medium)
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:L
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-611 - Improper Restriction of XML External Entity Reference
Assigner
References
Impacted products
Vendor Product Version
mcdope pam_usb Affected: < 0.9.2
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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