CVE-2026-47272

Authentication bypass via flawed OTP pad handling

Published May 27, 2026 · Updated May 27, 2026

Improper authentication in mcdope pam_usb before 0.9.0 allows local users to bypass USB authentication through faulty OTP handling. The pusb_pad_compare() function in src/pad.c fails to require both pad files, while generateRandom() can write uninitialized stack bytes after a short /dev/random read. A local user can delete an unreadable user-side pad to avoid physical-device verification; RNG failures can also make stored pad data predictable or attacker-influenced.

CVSS severity7.1
High
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in mcdope pam_usb before 0.9.0 allows local users to bypass USB authentication through faulty OTP handling. The pusb_pad_compare() function in src/pad.c fails to require both pad files, while generateRandom() can write uninitialized stack bytes after a short /dev/random read. A local user can delete an unreadable user-side pad to avoid physical-device verification; RNG failures can also make stored pad data predictable or attacker-influenced.

The record

CVE
CVE-2026-47272
Published
May 27, 2026
Updated
May 27, 2026
Vendor
mcdope
Product
pam_usb
Classifications
CWE-908, CWE-287, T1556
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.9.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

mcdope · pam_usbversion=< 0.9.0

Published CVSS scores

7.1GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
CWE-287Improper Authentication
T1556Modify Authentication Process

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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