Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins contain a flaw in the tag_key validation logic that fails to enforce exact key-length matching. This allows crafted inputs where a tag prefix is incorrectly treated as a full match. A remote attacker with authenticated or exposed access to these input endpoints can exploit this behavior to manipulate tags and redirect records to unintended destinations. This compromises the authenticity of ingested logs and can allow injection of forged data, alert flooding and routing manipulation.
References
History

Wed, 26 Nov 2025 11:15:00 +0000

Type Values Removed Values Added
First Time appeared Fluentbit
Fluentbit fluent Bit
Vendors & Products Fluentbit
Fluentbit fluent Bit

Mon, 24 Nov 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 24 Nov 2025 14:45:00 +0000

Type Values Removed Values Added
Description Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins contain a flaw in the tag_key validation logic that fails to enforce exact key-length matching. This allows crafted inputs where a tag prefix is incorrectly treated as a full match. A remote attacker with authenticated or exposed access to these input endpoints can exploit this behavior to manipulate tags and redirect records to unintended destinations. This compromises the authenticity of ingested logs and can allow injection of forged data, alert flooding and routing manipulation.
Title CVE-2025-12978
References

cve-icon MITRE

Status: PUBLISHED

Assigner: certcc

Published: 2025-11-24T14:42:06.305Z

Updated: 2025-11-24T15:29:06.000Z

Reserved: 2025-11-10T18:57:32.141Z

Link: CVE-2025-12978

cve-icon Vulnrichment

Updated: 2025-11-24T15:10:53.870Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-11-24T15:15:46.873

Modified: 2025-11-25T22:16:16.690

Link: CVE-2025-12978

cve-icon Redhat

No data.