Vulnerability Description
Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins fail to sanitize tag_key inputs. An attacker with network access or the ability to write records into Splunk or Elasticsearch can supply tag_key values containing special characters such as newlines or ../ that are treated as valid tags. Because tags influence routing and some outputs derive filenames or contents from tags, this can allow newline injection, path traversal, forged record injection, or log misrouting, impacting data integrity and log routing.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Treasuredata | Fluent Bit | 4.1.0 |
Related Weaknesses (CWE)
References
- https://fluentbit.io/blog/2025/10/28/security-vulnerabilities-addressed-in-fluen
- https://www.oligo.security/blog/critical-vulnerabilities-in-fluent-bit-expose-cl
FAQ
What is CVE-2025-12977?
CVE-2025-12977 is a vulnerability with a CVSS score of 9.1 (CRITICAL). Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins fail to sanitize tag_key inputs. An attacker with network access or the ability to write records into Splunk or Elasticsearch can supp...
How severe is CVE-2025-12977?
CVE-2025-12977 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2025-12977?
Check the references section above for vendor advisories and patch information. Affected products include: Treasuredata Fluent Bit.