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CVE-2025-12978

MEDIUMCVSS 5.4/10EPSS 0.34%

Last modified

CVE-2025-12978 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. 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. EPSS estimates a 0.34% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

EPSS Probability
0.34%

25.9th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

VendorProductVersions
TreasuredataFluent Bit4.1.0

References

Timeline

Published
Last Modified
Status
Analyzed

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 score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.34% probability of exploitation in the next 30 days.
How do I fix CVE-2025-12978?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-12978?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST