CVE-2025-12978

The record

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.

Affected packages

Related vulnerabilities

• CVE-2025-12970 The extract_name function in Fluent Bit in_docker input plugin copies container names… Also affects fluent-bit
• CVE-2025-12969 Fluent Bit in_forward input plugin does not properly enforce the security.users… Also affects fluent-bit
• CVE-2025-12972 Fluent Bit out_file plugin does not properly sanitize tag values when deriving output… Also affects fluent-bit
• CVE-2025-12977 Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins fail to sanitize… Also affects fluent-bit