CVE-2025-12978
CVE-2025-12978 is a medium-severity vulnerability in Treasuredata Fluent Bit with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: Medium (CVSS 3.x base score 5.4)
- EPSS exploit prediction: 0% (26th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-198807
- Affected product: Treasuredata Fluent Bit
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2025-12978?
- 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.
- How severe is CVE-2025-12978?
- CVE-2025-12978 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.
- Is CVE-2025-12978 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-12978?
- CVE-2025-12978 affects Treasuredata Fluent Bit. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2025-12978?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2025-12978 have an EU (EUVD) identifier?
- Yes. CVE-2025-12978 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-198807.
- When was CVE-2025-12978 published?
- CVE-2025-12978 was published on 2025-11-24 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:treasuredata:fluent_bit:4.1.0:*:*:*:*:*:*:*
More vulnerabilities in Treasuredata Fluent Bit
- CVE-2024-4323 — Critical (CVSS 9.8): A memory corruption vulnerability in Fluent Bit versions 2.0.7 thru 3.0.3. This issue lies in the embedded http…
- CVE-2021-36088 — Critical (CVSS 9.8): Fluent Bit (aka fluent-bit) 1.7.0 through 1.7.4 has a double free in flb_free (called from flb_parser_json_do and…
- CVE-2025-12977 — Critical (CVSS 9.1): Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins fail to sanitize tag_key inputs. An attacker with…
- CVE-2025-12970 — High (CVSS 8.8): The extract_name function in Fluent Bit in_docker input plugin copies container names into a fixed size stack buffer…
- CVE-2021-46879 — High (CVSS 7.8): An issue was discovered in Treasure Data Fluent Bit 1.7.1, a wrong variable is used to get the msgpack data resulting…
- CVE-2021-46878 — High (CVSS 7.8): An issue was discovered in Treasure Data Fluent Bit 1.7.1, erroneous parsing in flb_pack_msgpack_to_json_format leads…