# CVE-2026-48984: pam_usb: xfree() does not call explicit_bzero — sensitive cryptographic material may linger in freed heap

> Failure to zero memory before freeing in pam_usb may allow recovery of sensitive authentication material from heap memory.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Jun 2026
- **Updated:** 18 Jun 2026
- **Also known as:** GHSA-rmp6-wfrq-wrrc

## What is CVE-2026-48984?

CVE-2026-48984 is a medium-severity vulnerability in mcdope pam_usb, published on 18 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

pam_usb provides hardware authentication for Linux using ordinary removable media. In versions 0.9.1 and below, the xfree() memory release helper in calls free() without first zeroing the buffer contents, releasing heap-allocated buffers containing sensitive data — including one-time pad bytes read from disk — without clearing, leaving the sensitive content in freed heap memory until it happens to be overwritten by a subsequent allocation. On a system where a use-after-free condition exists, or where a heap inspection primitive becomes available, this could allow recovery of pad values or other authentication material from freed memory regions. This is a defence-in-depth requirement consistent with prior hardening work in this codebase (GHSA-vx6f-rrqr-j87c applied explicit_bzero to some pad paths; this issue generalises the pattern to the central deallocation helper).

Weakness: CWE-226 (Sensitive Information in Resource Not Removed Before Reuse), CWE-14 (Compiler Removal of Code to Clear Buffers)

## Which versions are affected by CVE-2026-48984?


## How do I fix CVE-2026-48984?

No fix has been published for CVE-2026-48984 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-48984 being exploited?

There is no known exploitation of CVE-2026-48984 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48984 and fix it if it is affected.

What it is: CVE-2026-48984 is a medium-severity vulnerability in mcdope pam_usb, published on 18 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-48984 in the wild and no public exploit code.

Affected product: mcdope pam_usb. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-48984/ (Markdown: https://insights.sbomify.com/CVE-2026-48984/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48984
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48984
- OSV: https://osv.dev/vulnerability/CVE-2026-48984

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48984/
Summaries are generated and may contain mistakes; the official description above is the record.