CVE-2026-47270: mcdope pam_usb · Race Condition
Affects mcdope pam_usbSource CVE Database V5
Not known to be exploited · CVSS 6.3 Medium : upgrade to 0.9.0 when convenient.
Data as of 30 Oct 2026, 11:52 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 0.9.0
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 27 May 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 30 Oct 2026.
What to do
Upgrade pam_usb and mcdope/pam_usb to 0.9.0.
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
A fix is available in pam_usb version 0.9.0. Users should upgrade to version 0.9.0 or later to remediate this vulnerability. No other mitigation is specified.
Description
pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0, pam_usb is a PAM module loaded into the host process (sudo, login, GDM, GNOME Shell). Display managers such as GDM run multiple concurrent authentication threads. Three functions used by the deny_remote feature called the non-reentrant strtok(), which stores state in a single global pointer. If two authentications race, one thread's strtok() call can overwrite the other's in-progress tokenisation pointer, causing incorrect parsing of the tmux session data or the /proc environ scan that backs the remote-session detection logic. Additionally, pusb_tmux_get_client_tty() passed the raw pointer returned by getenv(TMUX) directly to strtok(). getenv() returns a pointer into the live process environment block; strtok() inserts NUL bytes into that block, permanently corrupting the TMUX variable for subsequent code running in the same process. In long-lived display managers this affects all future authentications in that process. The combined effect can cause deny_remote=true to return an incorrect decision for a remote session, or an incorrect decision for a local session, depending on thread interleaving. This vulnerability is fixed in 0.9.0.