CVE-2025-12977
criticalpriority · track · 0EPSS 0.007 · 54 %ileDEEURUUSEPSS · scored 2026-10-23
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8.3–9.1
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (7)
Products and version ranges known to be affected.
advisories (2)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2025-2670Fluent Bit: Mehrere SchwachstellenDeutsch2025-11-24csaf · cert_bundDE
Ein entfernter anonymer oder authentisierter Angreifer kann mehrere Schwachstellen in Fluent Bit ausnutzen, um Sicherheitsmaßnahmen zu umgehen, beliebigen Code auszuführen, einen Denial-of-Service-Zustand zu verursachen, Daten zu manipulieren und vertrauliche Informationen offenzulegen.
- BIT-fluent-bit-2025-12977CVE-2025-129772025-12-01vendor · osvUS
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.
also known as (4)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (7)
External citations — patches, advisories, analysis.
- https://access.redhat.com/security/cve/cve-2025-12977cnnvd
- https://fluentbit.io/announcements/v4.1.0/cnnvd
- https://github.com/fluent/fluent-bit/releasesPatchcnnvd
- https://fluentbit.io/blog/2025/10/28/security-vulnerabilities-addressed-in-fluent-bit-v4.1-and-backported-to-v4.0/enisa_euvd
- https://www.oligo.security/blog/critical-vulnerabilities-in-fluent-bit-expose-cloud-environments-to-remote-takeoverenisa_euvd
- https://fluentbit.io/blog/2025/10/28/security-vulnerabilities-addressed-in-fluent-bit-v4.1-and-backported-to-v4.0/nvd
- https://www.oligo.security/blog/critical-vulnerabilities-in-fluent-bit-expose-cloud-environments-to-remote-takeovernvd
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan