SecuriTricks - CVE-2025-12977

Description

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.

Product(s) Impacted

Vendor	Product	Versions
Fluentbit	Fluent Bit In Http In Splunk In Elasticsearch	* * * *

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-1287

Improper Validation of Specified Type of Input

The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	fluentbit	fluent_bit	/	/	/	/	/	/	/	/
a	fluentbit	in_http	/	/	/	/	/	/	/	/
a	fluentbit	in_splunk	/	/	/	/	/	/	/	/
a	fluentbit	in_elasticsearch	/	/	/	/	/	/	/	/

References

https://fluentbit.io/announcements/v4.1.0/

CVSS Score

9.1 / 10

CVSS Data - 3.1

Attack Vector: NETWORK
Attack Complexity: LOW
Privileges Required: NONE
Scope: UNCHANGED
Confidentiality Impact: HIGH
Integrity Impact: HIGH
Availability Impact: NONE

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

View Vector String

Timeline

Published: Nov. 24, 2025, 3:15 p.m.
Last Modified: Nov. 25, 2025, 10:16 p.m.

Status : Awaiting Analysis

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

cret@cert.org

CVE-2025-12977