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MQTT does not validate hostnames

High severity GitHub Reviewed Published Nov 6, 2025 to the GitHub Advisory Database • Updated Nov 6, 2025

Package

bundlermqtt (RubyGems)

Affected versions

< 0.7.0

Patched versions

0.7.0

Description

A flaw was found in Rubygem MQTT. By default, the package used to not have hostname validation, resulting in possible Man-in-the-Middle (MITM) attack.

References

Published by the National Vulnerability DatabaseNov 6, 2025
Published to the GitHub Advisory Database Nov 6, 2025
Last updated Nov 6, 2025
Reviewed Nov 6, 2025

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector:More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity:More severe for the least complex attacks.
Privileges required:More severe if no privileges are required.
User interaction:More severe when no user interaction is required.
Scope:More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality:More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity:More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability:More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(19th percentile)

Weaknesses

Path Traversal: '..filename'

The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize '..filename' (leading backslash dot dot) sequences that can resolve to a location that is outside of that directory. Learn more on MITRE.

CVE ID

CVE-2025-12790

GHSA ID

GHSA-9c5q-w6gr-fxcq

Source code

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