Multiple vulnerabilities addressed in Fluentd v1.19.3, including critical RCE flaw CVE

Fluentd is an open-source data collection and log aggregation platform widely used to collect, process, and forward logs across cloud, enterprise, and containerized environments. Multiple vulnerabilities addressed in Fluentd v1.19.3 could allow unauthenticated remote attackers to achieve remote code execution, access sensitive information, or perform server-side request forgery (SSRF) under specific configurations. Successful exploitation typically requires affected instances to process untrusted input or use vulnerable placeholder expansion features.

The impact to confidentiality, integrity, and availability is high . Successful exploitation could allow attackers to execute arbitrary code, access sensitive operational data, interact with internal services, or disrupt logging operations. In environments where Fluentd is deployed as a centralized logging component, compromise could affect multiple connected systems and expose sensitive infrastructure information.

There is currently no public evidence of exploitation in the wild.

This weakness allows attackers to conduct the following:

2. Exploitation - Due to insufficient validation of user-controlled input in the ${tag} placeholder and missing authentication on the Monitor Agent API, attackers can manipulate output file paths, redirect outbound HTTP request destinations, or directly query exposed plugin internals.

3. Execute / Post-Compromise - Successful exploitation may allow attackers to execute arbitrary code, access sensitive configuration data, interact with internal services.

Patch The Centre for Cybersecurity Belgium strongly recommends installing updates for vulnerable devices with the highest priority after thorough testing.

Monitor/Detect The CCB recommends organizations upscale monitoring and detection capabilities to identify any related suspicious activity and ensure a swift response in case of an intrusion.

In case of an intrusion, you can report an incident via .

While patching appliances or software to the newest version may protect against future exploitation, it does not remediate historic compromise.

Tenable -