CVE-2025-12977: Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins fail to sanitize tag_key inputs. An attacker with network access or the ability to write…

PriorityP356critical9.1CVSS 3.1

AVNACLPRNUINSUCHIHAN

EPSS

0.63%

45.7th percentile

Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins fail to sanitize tag_key inputs. An attacker with network access or the ability to write records into Splunk or Elasticsearch can supply tag_key values containing special characters such as newlines or ../ that are treated as valid tags. Because tags influence routing and some outputs derive filenames or contents from tags, this can allow newline injection, path traversal, forged record injection, or log misrouting, impacting data integrity and log routing.

Affected

5 ranges

Vendor	Product	Version range	Fixed in
fluentbit	fluent_bit	< 4.0.12	4.0.12
msrc	azl3_fluent-bit_3.1.10-2_on_azure_linux_3.0	—	—
msrc	azl3_fluent-bit_3.1.9-6_on_azure_linux_3.0	—	—
msrc	cbl2_fluent-bit_3.0.6-4_on_cbl_mariner_2.0	—	—
treasuredata	fluent_bit	—	—

CVSS provenance

nvdv3.19.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

vendor_msrc8.3HIGH

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