Encoding Flaw in Eclipse Paho Go MQTT Library Affects Data Transmission

CVE-2025-10543

What is CVE-2025-10543?

The Eclipse Paho Go MQTT library, specifically versions up to 1.5.0, contains an encoding flaw related to UTF-8 strings. When strings exceed 65535 bytes, the conversion from an int64/int32 to an int16 fails to adequately check for overflows, resulting in potential packet corruption. This flaw may cause data intended for one field to unintentionally appear in another, which can lead to the leakage of sensitive information, particularly where an MQTT topic spills into the message body during packet transmission.

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