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OS Command InjectionWeakness · CWE-78

CVE-2026-44709

HIGH · 7.8 CVSS v3.1 Published 2026-05-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.8.7, pamusb-pinentry reads the PINENTRY_FALLBACK_APP environment variable and executes it directly without any validation. Any process that can set environment variables before pamusb-pinentry is invoked can point PINENTRY_FALLBACK_APP at an arbitrary binary or script and have it executed with the privileges of the pam_usb tool chain. This vulnerability is fixed in 0.8.7.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

pamusb-pinentry in pam_usb versions prior to 0.8.7 directly executes the binary specified in the PINENTRY_FALLBACK_APP environment variable without any validation, allowing local privilege escalation by having a process set this variable to point to an arbitrary executable.

MitigationUpgrade pam_usb to version 0.8.7 or later. As a workaround, ensure untrusted processes cannot influence the environment of pamusb-pinentry and audit for any processes that might set PINENTRY_FALLBACK_APP.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check pam_usb version
    Run 'dpkg -l pam-usb' or 'rpm -qi pam_usb' or 'pacman -Qi pam_usb' to retrieve the installed version of pam_usb
    Affected if The version is lower than 0.8.7 or the package is not found (not installed)
  2. Locate pamusb-pinentry binary
    Run 'which pamusb-pinentry' or 'find /usr -name pamusb-pinentry 2>/dev/null' to find the pamusb-pinentry binary
    Affected if The binary exists on the system
  3. Verify PINENTRY_FALLBACK_APP environment variable usage
    Audit running processes and their environment variables using 'ps aux | grep pamusb' or check PAM configuration for pamusb-pinentry invocations; examine if any process has PINENTRY_FALLBACK_APP set using 'printenv | grep PINENTRY'
    Affected if PINENTRY_FALLBACK_APP is set in the environment of any process that invokes pamusb-pinentry
  4. Check PAM configuration for pam_usb
    Review /etc/pam.d/ for any files referencing 'pam_usb' or 'pamusb' to determine if pam_usb is configured as an authentication mechanism
    Affected if pam_usb is configured in any PAM service file and the version is below 0.8.7

The system is affected if pam_usb version is prior to 0.8.7, pamusb-pinentry is present, and the PINENTRY_FALLBACK_APP environment variable can be influenced by an untrusted user context.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade pam_usb to version 0.8.7 or later. As a workaround, ensure untrusted processes cannot influence the environment of pamusb-pinentry and audit for any processes that might set PINENTRY_FALLBACK_APP.

Recommended fix High confidence

pam_usb version 0.8.7

  1. 1. Identify the current installed version of pam_usb by checking your package manager or running: dpkg -l | grep pam-usb or rpm -qa | grep pam-usb
  2. 2. Upgrade pam_usb to version 0.8.7 or later. For Debian/Ubuntu systems: sudo apt-get update && sudo apt-get install pam-usb (or sudo apt-get upgrade pam-usb)
  3. 3. For other distributions, download the source from the official repository and compile/install version 0.8.7 or later
  4. 4. Verify the upgraded version is 0.8.7 or higher using: dpkg -l | grep pam-usb or pamusb-version

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,570
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-44709 in production — separate from our analysis above.

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What this is

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