CVE-2021-27657

What it is

Successful exploitation of this vulnerability could give an authenticated Metasys user an unintended level of access to the server file system, allowing them to access or modify system files by sending specifically crafted web messages to the Metasys system. This issue affects: Johnson Controls Metasys version 11.0 and prior versions.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

1.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-06-04 15:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:45 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.2% in the next 30 days (EPSS).
• Severity: 8.8 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-06-04 15:15 UTC

Last modified

2026-06-17 03:45 UTC

Exploit probability

1.2% · EPSS, next 30 days

Weakness

CWE-269 · Improper privilege management

Record status

Modified

Affected

• Johnsoncontrols Metasys ≤ 11.0

Attack profile CVSS 3.1 · 8.8

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-27657.md and follow it. Check whether this project is affected by CVE-2021-27657. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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