CVE-2026-44161
Prior to 1.19.3, the Fluentd out_http output plugin allows placeholders such as ${tag} in the endpoint configuration parameter, and if a placeholder value is derived from untrusted input an attacker can control the destination hostname of outbound HTTP…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.44%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Fluentd collects events from various data sources and writes them to files, RDBMS, NoSQL, IaaS, SaaS, Hadoop and so on. Prior to 1.19.3, the Fluentd out_http output plugin allows placeholders such as ${tag} in the endpoint configuration parameter, and if a placeholder value is derived from untrusted input an attacker can control the destination hostname of outbound HTTP requests and force requests to arbitrary internal services. This issue is fixed in version 1.19.3.
- CVSS 3.1
- 7.2 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L
- EPSS
- 0.44% probability · 37th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-918
- Affected
- fluentd/fluentd
- Source
- security-advisories@github.com
References
- https://github.com/fluent/fluentd/commit/c6a01ea2e0ea01977f8d615f7c6dbfae4cba88c9Patch
- https://github.com/fluent/fluentd/pull/5394Issue Tracking, Patch
- https://github.com/fluent/fluentd/releases/tag/v1.19.3Product, Release Notes
- https://github.com/fluent/fluentd/security/advisories/GHSA-72f5-rr8c-r6grMitigation, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.