CVE-2018-18556

CRITICALNVD 9.99.9—
EchelonGraph scoreMEDIUM confidence

Score 9.9 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-13. NVD baseline CVSS 9.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Weaponized
9.9EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • Public exploit code is available (Metasploit, epss top5pct, public exploit)
CISA-KEV: Not listedEPSS PROB: 15%CVSS: 9.9Exploit: Metasploit · epss top5pct · public exploitExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.9
EG Score
9.9(medium)
EG Risk
75(Track*)
EG Risk 75/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity99% × 45%
Exploitation65% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
15%
EPSS %ILE
97%
KEV
Not listed

Published

December 17, 2018

Last Modified

November 21, 2024

Advisory Details (3)

Auto-updated Aug 21, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

The "operator" level is proved insecure and will be removed in the next releases

https://blog.vyos.io/the-operator-level-is-proved-insecure-and-will-be-removed-in-the-next-releases
generic

CVE-2018-18556 - VyOS Privilege escalation via sudo pppd for operator users | Rich Mirch

https://blog.mirch.io/2018/11/05/cve-2018-18556-vyos-privilege-escalation-via-sudo-pppd-for-operator-users/
generic

Packet Storm Security

http://packetstormsecurity.com/files/159234/VyOS-restricted-shell-Escape-Privilege-Escalation.html

Data Freshness Timeline

(refreshed 6× in last 7d / 23× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-08-20 22:51 UTCEPSS rescore
  2. 2026-08-19 17:00 UTCEPSS rescore
  3. 2026-08-18 13:44 UTCEPSS rescore
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  22. 2026-07-23 01:34 UTCEG score recompute
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  24. 2026-07-22 14:05 UTCEPSS rescore
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  1. 2026-07-20 17:04 UTCEPSS rescore
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  26. 2026-06-30 23:20 UTCEPSS rescore
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  45. 2026-06-18 17:50 UTCEPSS rescore
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  65. 2026-06-01 13:50 UTCEPSS rescore
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  67. 2026-05-31 00:14 UTCEPSS rescore
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  69. 2026-05-28 13:42 UTCEPSS rescore
  70. 2026-05-28 13:42 UTCEPSS rescore
  71. 2026-05-28 00:13 UTCEG score recompute
  72. 2026-05-28 00:13 UTCGHSA enrichment
  73. 2026-05-27 13:38 UTCEPSS rescore
  74. 2026-05-27 13:38 UTCEPSS rescore
  75. 2026-05-26 13:42 UTCEPSS rescore

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Metasploit module). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Metasploitexploit/linux/ssh/vyos_restricted_shell_privesc✓ verified
    First seen Nov 5, 2018

    VyOS restricted-shell Escape and Privilege Escalation

    Open source ↗

Frequently asked(5)

What is CVE-2018-18556?
CVE-2018-18556 is a critical vulnerability published on December 17, 2018. 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…
When was CVE-2018-18556 disclosed?
CVE-2018-18556 was first published in the National Vulnerability Database on December 17, 2018, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2018-18556 actively exploited?
CVE-2018-18556 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 15% probability of exploitation in the next 30 days, which ranks it in the top 3.5% of all scored CVEs.
What is the CVSS score of CVE-2018-18556?
CVE-2018-18556 has a CVSS v3 base score of 9.9 (NVD).
How do I remediate CVE-2018-18556?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-18556, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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