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CVE-2026-47269— pam_usb: deny_remote feature incorrectly classifies IPv4-mapped IPv6 remote connections as local

Quick assessment

Affected
mcdope pam_usb
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

pam_usb是McDope个人开发者的一个基于USB设备的Linux硬件认证工具。 pam_usb 0.9.0之前版本存在访问控制错误漏洞，该漏洞源于deny_remote功能仅检查ut_addr_v6的第一个32位字，可能导致远程认证绕过。

CVSS 7.4 · High EPSS 0.45% · P37

Affected Version Matrix 1

VendorProduct Version RangeStatus
mcdope pam_usb < 0.9.0 affected
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I. Basic Information for CVE-2026-47269

Vulnerability Information
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Vulnerability Title
pam_usb: deny_remote feature incorrectly classifies IPv4-mapped IPv6 remote connections as local
Source: CVE Program / CVE List V5
Vulnerability Description
pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0, pam_usb's deny_remote feature checks utmpx ut_addr_v6 to detect whether an authentication request originates from a remote session. The outer guard was if (utent->ut_addr_v6[0] != 0), which only tests the first 32-bit word of the 128-bit address field. IPv4-mapped IPv6 addresses (::ffff:x.x.x.x) store the IPv4 address in ut_addr_v6[3] with ut_addr_v6[0] == 0. On systems where the SSH daemon listens on :: (IPv6 wildcard) with AddressFamily any -- common on Ubuntu and Debian -- incoming IPv4 connections are recorded in utmpx as IPv4-mapped IPv6 addresses. The outer check evaluates to false, the remote-detection block is skipped entirely, and the session is treated as local. deny_remote=true does not block the authentication. An attacker with physical access to a registered USB device can authenticate over SSH on an affected system as if they were sitting at a local terminal, bypassing the deny_remote restriction. This vulnerability is fixed in 0.9.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
访问控制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
pam_usb 访问控制错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
pam_usb是McDope个人开发者的一个基于USB设备的Linux硬件认证工具。 pam_usb 0.9.0之前版本存在访问控制错误漏洞，该漏洞源于deny_remote功能仅检查ut_addr_v6的第一个32位字，可能导致远程认证绕过。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
mcdope pam_usb < 0.9.0 -

II. Public POCs for CVE-2026-47269

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 8679 chars
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III. Intelligence Information for CVE-2026-47269

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Patches & Fixes for CVE-2026-47269 (1)

Vendor Advisories for CVE-2026-47269 (1)

Same Patch Batch · mcdope · 2026-05-27 · 15 CVEs total

CVE-2026-44713 8.8 HIGH pam_usb: Command injection via $TMUX environment variable leads to RCE as root
CVE-2026-44712 8.2 HIGH pam_usb: Shell injection via device UUID and username in pamusb-conf and pamusb-agent
CVE-2026-48064 8.1 HIGH pam_usb: PAM_RHOST check skipped when deny_remote=false allows XDMCP authentication bypass
CVE-2026-44711 7.9 HIGH pam_usb: Symlink attacks on pad directory and pad files enable authentication bypass and r
CVE-2026-44709 7.8 HIGH pam_usb: PINENTRY_FALLBACK_APP environment variable allows arbitrary command execution
CVE-2026-47272 7.1 HIGH pam_usb: OTP pad authentication bypass via missing system pad check and uninitialized RNG
CVE-2026-48065 6.7 MEDIUM pam_usb: Unchecked integer multiplication before xmalloc() in conf.c allows heap-based buf
CVE-2026-47273 6.5 MEDIUM pam_usb: XPath injection via PAM-supplied identifiers in pam_usb configuration queries
CVE-2026-47274 6.3 MEDIUM pam_usb: Uncontrolled search path in pam_usb tools allows privilege escalation via PATH ma
CVE-2026-47270 6.3 MEDIUM pam_usb: strtok() race condition in multi-threaded PAM hosts can corrupt deny_remote resul
CVE-2026-48066 5.7 MEDIUM pam_usb: Thread-unsafe static pointer in log.c causes data race under concurrent PAM authe
CVE-2026-47271 5.1 MEDIUM pam_usb: OOM guards removed by -DNDEBUG cause NULL dereference and authentication process
CVE-2026-44710 4.6 MEDIUM pam_usb: NULL pointer dereference from UDisks device fields causes PAM crash and login den
CVE-2026-48792 4.4 MEDIUM pam_usb: pusb_has_virtual_input_device() silently discards EACCES, disabling remote deskto

IV. Related Vulnerabilities

Same product: pam_usb
Same vendor: mcdope
Same weakness: CWE-284

V. Comments for CVE-2026-47269

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