Incorrect Comparison Affecting fluent/fluent-bit package, versions [,4.1.1)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-FLUENTFLUENTBIT-14107152
- published26 Nov 2025
- disclosed24 Nov 2025
- creditUnknown
Introduced: 24 Nov 2025
CVE-2025-12978 (opens in a new tab)How to fix?
Upgrade fluent/fluent-bit to version 4.1.1 or higher.
Overview
Affected versions of this package are vulnerable to Incorrect Comparison due to incorrect key length matching in the tag_key validation logic of the in_http, in_splunk, and in_elasticsearch input plugins. An attacker can manipulate log tags and redirect records to unintended destinations by sending crafted inputs to the affected endpoints, potentially compromising log authenticity, injecting forged data, causing alert flooding, and manipulating routing.