CVE-2026-48983: mcdope pam_usb · Time-of-check Time-of-use (TOCTOU) Race Condition
Affects mcdope pam_usbSource CVE Database V5
Not known to be exploited · CVSS 5.8 Medium : upgrade to 0.9.2 when convenient.
Data as of 31 Oct 2026, 20:20 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.9.2
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:LExploitation evidence
Disclosed: evidence found.
CVE published 18 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.
What to do
Upgrade pam_usb and mcdope/pam_usb to 0.9.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| mcdopepam_usb | Affected
| Fixed in
|
GitHubmcdope/pam_usbpkg:github/mcdope/pam_usbOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade pam_usb to version 0.9.2 or later, where this TOCTOU race condition has been fixed. No other mitigation or workaround is indicated.
Description
pam_usb provides hardware authentication for Linux using ordinary removable media. In versions prior to 0.9.2, a symlink race condition exists in per-device and per-user pad directory creation. pam_usb uses a check-then-act pattern: it calls lstat() to test for existence and then calls mkdir() separately to create the directory. A local attacker can win the race between these calls by replacing the target path with a symlink to a directory they control. If successful, one-time pad files may be written to an attacker-controlled location, potentially exposing future pad values before use or disrupting authentication. This issue has been fixed in version 0.9.2.