Home / Threat Intelligence bulletins / Critical vulnerability in Fluent Bit

Target Industry

Indiscriminate, opportunistic targeting.


Fluent Bit is an open-source, lightweight log processor with compatibility across operating systems and web services. The agent is utilised by all major cloud providers including Google Cloud, Microsoft, Amazon Web Services (AWS), Splunk, and Cisco. A severe security flaw has been discovered that arose from a critical memory corruption vulnerability within Fluent Bit’s built-in HTTP server. Tracked as CVE-2024-4323 (CVSS 3.1 base score: 9.8) and referred to as “Linguistic Lumberjack”, the relevant security update should be applied as a matter of urgency where possible.


Successful exploitation of CVE-2024-4323 could allow attackers to carry out denial-of-service (DoS) attacks, capture sensitive information and conduct remote code execution.

Targeted Organisations

As of the time of writing, no specific organisations were targeted apart from Fluent Bit.

Affected Products

Fluent Bit versions 2.0.7 to 3.0.3.

Containment, Mitigations & Remediations

It is strongly recommended that the updated Fluent Bit main branch is merged as soon as possible, with the release of version 3.0.4 also expected to include the fix.

Indicators of Compromise

No specific Indicators of Compromise (IoCs) are available currently.

Threat Landscape

Fluent Bit occupies a significant portion of telemetry processing utilisation. Given that threat actors generally utilise a combination of probability and asset value to determine which attack surfaces to focus on, Fluent Bit is a prime target. Due to the fact that Fluent Bit has become an integral aspect of business operations, threat actors will continue to exploit vulnerabilities contained within the associated products in an attempt to extract the sensitive data contained therein.

Threat Group

No attribution to specific threat actors or groups has been identified at the time of writing.

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