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CVE-2026-48982— pam_usb: Missing O_EXCL on pad temp file creation allows concurrent update race

CVSS 5.8 · Medium EPSS 0.09% · P0

Affected Version Matrix 1

VendorProductVersion RangeStatus
mcdopepam_usb< 0.9.2affected
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I. Basic Information for CVE-2026-48982

Vulnerability Information
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Vulnerability Title
pam_usb: Missing O_EXCL on pad temp file creation allows concurrent update race
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, when updating a one-time pad file, a temporary file is created using open() without the O_EXCL flag. Without O_EXCL, the create operation is not atomic: two concurrent processes racing to update the same pad may both succeed in opening the file, with the second write silently overwriting the first. The one-time pad is the core replay-prevention mechanism of pam_usb. A successful race could result in the stored pad value diverging from what either process expected, potentially causing authentication failures or, in a precisely timed attack, creating a window for pad reuse. 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:L/UI:N/S:U/C:L/I:H/A:L
Source: NVD (National Vulnerability Database)
Vulnerability Type
使用共享资源的并发执行不恰当同步问题(竞争条件)
Source: NVD (National Vulnerability Database)
Vulnerability Title
McDope pam_usb 竞争条件问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
mcdope pam_usb是mcdope的认证模块。 McDope pam_usb 0.9.2之前版本存在竞争条件问题漏洞，该漏洞源于更新一次性密码本文件时使用open()函数未设置O_EXCL标志，导致竞争条件，可能造成身份验证失败或密码本重用。
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

VendorProductAffected VersionsCPESubscribe
mcdopepam_usb < 0.9.2 -

II. Public POCs for CVE-2026-48982

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III. Intelligence Information for CVE-2026-48982

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Patches & Fixes for CVE-2026-48982 (1)

Vendor Advisories for CVE-2026-48982 (1)

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

CVE-2026-489816.7 MEDIUMpam_usb: xmlReadFile flags=0 permits XXE network entity fetching in conf.c
CVE-2026-489806.3 MEDIUMpam_usb: getenv() used in PAM context allows environment variable injection into local-che
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-362

V. Comments for CVE-2026-48982

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