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CVE-2026-48981— pam_usb: xmlReadFile flags=0 permits XXE network entity fetching in conf.c

CVSS 6.7 · Medium EPSS 0.01% · P3

Affected Version Matrix 1

VendorProductVersion RangeStatus
mcdopepam_usb< 0.9.2affected
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I. Basic Information for CVE-2026-48981

Vulnerability Information
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Vulnerability Title
pam_usb: xmlReadFile flags=0 permits XXE network entity fetching in conf.c
Source: NVD (National Vulnerability Database)
Vulnerability 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.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:L
Source: NVD (National Vulnerability Database)
Vulnerability Type
XML外部实体引用的不恰当限制(XXE)
Source: NVD (National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
mcdopepam_usb < 0.9.2 -

II. Public POCs for CVE-2026-48981

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III. Intelligence Information for CVE-2026-48981

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Patches & Fixes for CVE-2026-48981 (1)

Vendor Advisories for CVE-2026-48981 (1)

Same Patch Batch · mcdope · 2026-06-18 · 7 CVEs total

CVE-2026-489806.3 MEDIUMpam_usb: getenv() used in PAM context allows environment variable injection into local-che
CVE-2026-489825.8 MEDIUMpam_usb: Missing O_EXCL on pad temp file creation allows concurrent update race
CVE-2026-489835.8 MEDIUMpam_usb: TOCTOU race condition in pad directory creation allows symlink substitution
CVE-2026-489855.5 MEDIUMpam_usb: NULL Dereference Crash in pusb_is_loginctl_local when loginctl Returns Empty Remo
CVE-2026-489844.7 MEDIUMpam_usb: xfree() does not call explicit_bzero — sensitive cryptographic material may linge
CVE-2026-489864.7 MEDIUMpam_usb: Infinite loop DoS in process-tree walk when parent process exits during authentic

IV. Related Vulnerabilities

Same product: pam_usb
Same vendor: mcdope
Same weakness: CWE-611

V. Comments for CVE-2026-48981

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