Fluent Bit Denial-of-Service Vulnerability via Use-After-Free in YAML Configuration Parsing

A use-after-free vulnerability has been identified in Fluent Bit version 3.7.2. This issue allows a local attacker to cause a denial-of-service by exploiting improper memory management during YAML configuration parsing. The vulnerability arises in the 'cfl_list_size' function, where memory is not correctly handled, leading to a heap-use-after-free condition. This can be reproduced by running Fluent Bit with a crafted YAML configuration that triggers the vulnerability.

Impact

Exploitation of this vulnerability leads to a denial-of-service condition, causing Fluent Bit to crash.

Reproduction

The vulnerability can be reproduced by running Fluent Bit with a configuration file that includes 'test/nested.yaml'. This file should be referenced in a 'poc.yaml' file under the 'includes' section. The 'env' section of the 'poc.yaml' file should be set to 'observability: calyptia'.