GHSA-32fw-gq77-f2f2

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    GHSA-32fw-gq77-f2f2

    Published: 2 Dec 2025Last Modified: 10 Sept 2026

    Summary: Eclipse Paho Go MQTT may incorrectly encode strings if length exceeds 65535 bytes

    Details: In Eclipse Paho Go MQTT v3.1 library (paho.mqtt.golang) versions <=1.5.0 UTF-8 encoded strings, passed into the library, may be incorrectly encoded if their length exceeds 65535 bytes. This may lead to unexpected content in packets sent to the server (for example, part of an MQTT topic may leak into the message body in a PUBLISH packet). The issue arises because the length of the data passed in was converted from an int64/int32 (depending upon CPU) to an int16 without checks for overflows. The int16 length was then written, followed by the data (e.g. topic). This meant that when the data (e.g. topic) was over 65535 bytes then the amount of data written exceeds what the length field indicates. This could lead to a corrupt packet, or mean that the excess data leaks into another field (e.g. topic leaks into message body).

    Affected packages

    Package

    Name: github.com/eclipse/paho.mqtt.golang

    Purl: pkg:golang/github.com/eclipse/paho.mqtt.golang

    Affected ranges

    Type: SEMVER

    Events:

    Introduced- 0
    Fixed -1.5.1

    Affected versions

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    GHSA-32fw-gq77-f2f2 | CVE-DB