CVE-2018-18555: A sandbox escape issue was discovered in VyOS 1.1.8

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CRITICAL 9.9MITIGATE

CVE-2018-18555 is a critical-severity flaw (CVSS 9.9) affecting vyos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A sandbox escape issue was discovered in VyOS 1.1.8. It provides a restricted management shell for operator users to administer the device. By issuing various shell special characters with certain commands, an authenticated operator user can break out of the management shell and gain access to the underlying Linux shell. The user can then run arbitrary operating system commands with the privileges afforded by their account.

Why this priority

Critical severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.9 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.8% (top 22%)
CISA exploited list	No
Weakness	CWE-78
Published	2018-12-17
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: vyos

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-12-17 19:29 UTCPublished CVE record published
2026-06-17 01:47 UTCUpdated Record last modified

vyos vyos MITIGATE

Affected: 1.1.8

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.1.8

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2018-18555?

vyos: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-18555 being exploited?

CVE-2018-18555 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-18555 affect?

CVE-2018-18555 affects vyos. Severity is 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 administer the device. By issuing various shell special characters with certain commands, an authenticated operator user ca

How urgent is CVE-2018-18555?

Priority 59/100. Critical severity; Public exploit reference

Related CVEs

CVE-2018-18556 CRITICAL 9.9 MITIGATE A privilege escalation issue was discovered in VyOS 1.1.8

References

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