CVE-2025-12969

Fluent Bit in_forward input plugin does not properly enforce the security.users authentication mechanism under certain configuration conditions. This allows remote attackers with network access to the Fluent Bit instance exposing the forward input to send unauthenticated data. By bypassing authentication controls, attackers can inject forged log records, flood alerting systems, or manipulate routing decisions, compromising the authenticity and integrity of ingested logs.

Score

CVSS 3.1 6.5 Medium

Status

Modified - cret@cert.org

Published

2025-11-24

Last modified

2026-10-08

Weaknesses

CWE-306

Affected products

• Fluent Bit (Fluentbit)
• Fluent Bit (Treasuredata)

References

• https://fluentbit.io/blog/2025/10/28/security-vulnerabilities-addressed-in-fluent-bit-v4.1-and-backported-to-v4.0/
• https://www.oligo.security/blog/critical-vulnerabilities-in-fluent-bit-expose-cloud-environments-to-remote-takeover