# CVE-2025-12978: Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins contain a flaw in the tag_key validation logic that…

Source: https://junglewise.ai/threats/cve-2025-12978-fluent-bit-in-http-in-splunk-and-in-elasticsearch-input-plugins  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-11-24  
License: CC BY 4.0 with a link back

CVE-2025-12978 · Severity: medium · CVSS 5.4 · Published 2025-11-24

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.

Technologies: [Treasuredata Fluent Bit](https://junglewise.ai/threats/technologies/treasuredata-fluent-bit). Vendors: [Treasuredata](https://junglewise.ai/threats/vendors/treasuredata).

## Quick answers

**Is CVE-2025-12978 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-12978 being exploited in the wild.

**How severe is CVE-2025-12978?** Medium severity, with a CVSS score of 5.4, published 24 November 2025.

**Which products and versions are affected?** Treasuredata Fluent Bit. The advisory does not name versions.

**Is there a fix for CVE-2025-12978?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2025-12978?** Check whether you run Treasuredata Fluent Bit. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Treasuredata Fluent Bit

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