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TI-2026-36240 Aliases CVE-2026-48984

pam_usb: xfree() does not call explicit_bzero — sensitive cryptographic material may linger in freed heap

Priority LOW 21CWE-14Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

pam_usb provides hardware authentication for Linux using ordinary removable media. In versions 0.9.1 and below, the xfree() memory release helper in calls free() without first zeroing the buffer contents, releasing heap-allocated buffers containing sensitive data — including one-time pad bytes read from disk — without clearing, leaving the sensitive content in freed heap memory until it happens to be overwritten by a subsequent allocation. On a system where a use-after-free condition exists, or where a heap inspection primitive becomes available, this could allow recovery of pad values or other authentication material from freed memory regions. This is a defence-in-depth requirement consistent with prior hardening work in this codebase (GHSA-vx6f-rrqr-j87c applied explicit_bzero to some pad paths; this issue generalises the pattern to the central deallocation helper).

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00147 3rd percentileScored 2026-11-07
Fix Fixed pam_usb (mcdope): 0.9.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
mcdopepam_usbbefore 0.9.20.9.2Patch availableCNA
  • pam_usb Vendormcdope Affected before 0.9.2 Fixed in 0.9.2 Patch available CNA

Remediation

  • Fix · CNA pam_usb (mcdope) Fixed in 0.9.2

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-48984

References

Other 2

  • TI-2026-35505 pam_usb: PAM_RHOST check skipped when deny_remote=false allows XDMCP authentication bypass CVSS 3.1HIGH 8.1
  • TI-2026-32598 pam_usb: Symlink attacks on pad directory and pad files enable authentication bypass and root file corruption CVSS 3.1HIGH 7.9
  • TI-2026-32596 pam_usb: PINENTRY_FALLBACK_APP environment variable allows arbitrary command execution CVSS 3.1HIGH 7.8
  • TI-2026-32600 pam_usb: Command injection via $TMUX environment variable leads to RCE as root CVSS 3.1HIGH 8.8
  • TI-2026-32599 pam_usb: Shell injection via device UUID and username in pamusb-conf and pamusb-agent CVSS 3.1HIGH 8.2
  • TI-2026-34849 pam_usb: deny_remote feature incorrectly classifies IPv4-mapped IPv6 remote connections as local CVSS 3.1HIGH 7.4
See all 21 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences