Cybersecurity researchers have uncovered five significant vulnerabilities in Fluent Bit, an open-source telemetry agent widely used for cloud environments. These vulnerabilities pose severe risks, including remote code execution, denial-of-service conditions, and the manipulation of logging data.
The vulnerabilities include:
- CVE-2025-12972: A path traversal issue that allows attackers to use unsanitized tag values for creating output filenames, potentially leading to log tampering and remote code execution.
- CVE-2025-12970: A stack buffer overflow vulnerability in the Docker Metrics input plugin, which could let attackers execute arbitrary code or crash the agent by creating container names that are excessively long.
- CVE-2025-12978: This flaw in tag-matching logic enables attackers to spoof trusted tags, allowing them to reroute logs and inject malicious records while bypassing filters.
- CVE-2025-12977: Inadequate input validation of tags allows attackers to inject newlines and control characters, corrupting logs downstream.
- CVE-2025-12969: The in_forward plugin has a missing authentication feature, which could let attackers send misleading logs and flood security products with illegitimate events.
Research indicates that exploiting these vulnerabilities could allow attackers to infiltrate deeper into cloud environments, execute harmful code through Fluent Bit, manipulate event records, and cover their tracks after an attack. The CERT Coordination Center has highlighted these issues, indicating a requirement for network access to the affected Fluent Bit instances.
Following responsible disclosure, updates have been released to remedy these vulnerabilities in versions 4.1.1 and 4.0.12. Amazon Web Services (AWS) has also advised its clients using Fluent Bit to upgrade to these new versions for maximum protection.
The existence of these vulnerabilities, especially in a popular service like Fluent Bit, raises serious concerns about the integrity of cloud services and the potential for data manipulation, theft, and loss of control over logging services. To mitigate these risks, best practices include restricting the use of dynamic tags, securing output paths, and running Fluent Bit in a non-root environment while keeping configuration files read-only.
The vulnerabilities emerge as a stark reminder of the ongoing cybersecurity challenges that cloud services face, following previous incidents such as the notable Linguistic Lumberjack vulnerability identified over a year ago.
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