CVE-2018-18556
CVE-2018-18556 is a critical-severity vulnerability in Vyos with a CVSS 3.x base score of 9.9. Its EPSS exploit-prediction score of 15% places it in the 96th percentile, indicating an elevated likelihood of exploitation.
Key facts
- Severity: Critical (CVSS 3.x base score 9.9)
- CVSS v2: 9.0
- EPSS exploit prediction: 15% (96th percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Vyos
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2018-18556?
- 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.
- How severe is CVE-2018-18556?
- CVE-2018-18556 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2018-18556 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 15% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2018-18556?
- CVE-2018-18556 affects Vyos. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2018-18556?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2018-18556 published?
- CVE-2018-18556 was published on 2018-12-17 and last updated on 2026-06-17.
References
- http://packetstormsecurity.com/files/159234/VyOS-restricted-shell-Escape-Privilege-Escalation.html
- https://blog.mirch.io/2018/11/05/cve-2018-18556-vyos-privilege-escalation-via-sudo-pppd-for-operator-users/
- https://blog.vyos.io/the-operator-level-is-proved-insecure-and-will-be-removed-in-the-next-releases
Affected products (1)
- cpe:2.3:o:vyos:vyos:1.1.8:*:*:*:*:*:*:*
More vulnerabilities in Vyos
- CVE-2018-18555 — Critical (CVSS 9.9): A sandbox escape issue was discovered in VyOS 1.1.8. It provides a restricted management shell for operator users to…