# CVE-2026-48985: pam_usb: NULL Dereference Crash in pusb_is_loginctl_local when loginctl Returns Empty Remote Field

> A NULL dereference in pam_usb causes a crash when parsing empty loginctl output, potentially denying access to authentication services.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **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-7j6h-wfc2-mg5q

## What is CVE-2026-48985?

CVE-2026-48985 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, pusb_is_loginctl_local() can cause a NULL dereference crash when parsing loginctl output. The function calls popen() and reads the result; if the Remote field is only a newline, fgets() succeeds but strtok_r(buf, "\n", &saveptr) returns NULL. A subsequent strcmp(is_remote, "no") then dereferences NULL, causing undefined behavior (typically SIGSEGV) and crashing the PAM module. This can crash the authenticating process (e.g., sudo, login) and, depending on PAM stack configuration, deny access for all users of the affected service. This issue has been fixed in version 0.9.2.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-48985?


## How do I fix CVE-2026-48985?

No fix has been published for CVE-2026-48985 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-48985 being exploited?

There is no known exploitation of CVE-2026-48985 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48985 and fix it if it is affected.

What it is: CVE-2026-48985 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-2026-48985 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-2026-48985/ (Markdown: https://insights.sbomify.com/CVE-2026-48985/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48985
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48985
- OSV: https://osv.dev/vulnerability/CVE-2026-48985

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-48985/
Summaries are generated and may contain mistakes; the official description above is the record.