Is CVE-2019-9749 actively exploited?

No active exploitation of CVE-2019-9749 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2019-9749 be exploited remotely?

Yes. CVE-2019-9749 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2019-9749?

CVE-2019-9749 has a CVSS score of 7.5 (HIGH).

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HIGH

CVE-2019-9749

CWE-681Published: March 13, 2019· Updated: Jun 17, 2026

7.5

CVSS v3.1

Official Description

An issue was discovered in the MQTT input plugin in Fluent Bit through 1.0.4. When this plugin acts as an MQTT broker (server), it mishandles incoming network messages. After processing a crafted packet, the plugin's mqtt_packet_drop function (in /plugins/in_mqtt/mqtt_prot.c) executes the memmove() function with a negative size parameter. That leads to a crash of the whole Fluent Bit server via a SIGSEGV signal.

NVD Source

Technical Analysis

CVE-2019-9749 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.