CVE-2026-44025: Fluentd Fluentd Is Vulnerable To Exposure Vulnerability

HIGH
Advisory Identifier: GHSA-pr7j-96cj-549h
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CVSS 7.5
CWE-306 CWE-200
Published
Advisory Summary

CVE-2026-44025 is a HIGH (CVSS 7.5) fluentd is vulnerable to exposure vulnerability (CWE-306: Missing Authentication for Critical Function) affecting Fluentd libraries in the RubyGems ecosystem. The issue involves fluentd is vulnerable to exposure of sensitive information via monitor agent api. Remediation is available by upgrading affected packages to version 1.19.3.

CVE-2026-44025 at a Glance

CVE Identifier CVE-2026-44025
GHSA Identifier GHSA-pr7j-96cj-549h
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-306: Missing Authentication for Critical Function
Affected Product Fluentd
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-44025

To remediate this vulnerability, upgrade all affected Fluentd dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

fluentd fixed: 1.19.3 
Upgrade fluentd to 1.19.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for fluentd

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-44025, inspect your project dependencies for Fluentd:

inspect dependencies for fluentd

Analyze the terminal output to locate any version of Fluentd in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.19.3), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-306: Missing Authentication for Critical Function, where the product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. In Fluentd, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Fluentd's Monitor Agent plugin (`in_monitor_agent`) exposes internal metrics and plugin information via a REST API. It was discovered that the API response (`/api/plugins.json` and related endpoints) unintentionally includes internal instance variables of loaded plugins. If any plugins store sensitive information—such as database passwords, API keys, or cloud credentials—in its instance variables, this information may be exposed in plain text to any user or system that has HTTP access to the Monitor Agent API. ### Impact This vulnerability allows for unauthorized information disclosure. An attacker who can reach the Monitor Agent API port (default: `24220`) can potentially extract sensitive credentials used by other Fluentd plugins. The impact severity depends highly on the network configuration (whether the Monitor Agent port is exposed to untrusted networks) and the specific plugins configured in the Fluentd instance. ### Patches: v1.19.3 ### Workarounds If usesrs cannot immediately update Fluentd to the patched version, they can mitigate this risk by strictly controlling access to the Monitor Agent port. Ensure the Monitor Agent is only bound to `localhost` (`127.0.0.1`) rather than `0.0.0.0`. ``` <source> @type monitor_agent bind 127.0.0.1 port 24220 </source> ``` Use firewall rules (e.g., iptables, AWS Security Groups) to block access to the Monitor Agent port (`24220`) from untrusted networks or instances.

CVE-2026-44025 Affected Fluentd Versions

1 component(s)
Fixed Versions:
1.19.3
Product / Package Ecosystem Affected Versions Fixed Version
fluentd
gem/fluentd
RubyGems
< 1.19.3
1.19.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/fluent/fluentd/security/advisories/GHSA-pr7j-96cj-549h
Fluentd Source Repository REPOSITORY
https://github.com/fluent/fluentd
Fluentd Release RELEASE
https://github.com/fluent/fluentd/releases/tag/v1.19.3

Frequently Asked Questions

What is CVE-2026-44025?
CVE-2026-44025 is a security vulnerability in Fluentd involving Fluentd is Vulnerable to Exposure of Sensitive Information via Monitor Agent API under CWE-306: Missing Authentication for Critical Function.
Which Fluentd versions are affected?
Affected versions include releases prior to 1.19.3 across affected packages: fluentd.
What version fixes CVE-2026-44025?
Upgrading to 1.19.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is fluentd affected?
Yes, fluentd is affected in releases prior to 1.19.3. Upgrade your dependency to 1.19.3 or later.
What is the CVSS score of CVE-2026-44025?
CVE-2026-44025 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-44025?
CVE-2026-44025 is classified under CWE-306: Missing Authentication for Critical Function (The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.).
How can I check RubyGems dependencies for CVE-2026-44025?
Run the dependency tree command: 'inspect dependencies for fluentd'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-pr7j-96cj-549h",
  "modified" : "2026-06-26T16:32:57Z",
  "published" : "2026-06-26T16:32:57Z",
  "aliases" : [ "CVE-2026-44025" ],
  "summary" : "Fluentd is Vulnerable to Exposure of Sensitive Information via Monitor Agent API",
  "details" : "Fluentd's Monitor Agent plugin (`in_monitor_agent`) exposes internal metrics and plugin information via a REST API.\nIt was discovered that the API response (`/api/plugins.json` and related endpoints) unintentionally includes internal instance variables of loaded plugins.\n\nIf any plugins store sensitive information—such as database passwords, API keys, or cloud credentials—in its instance variables,\nthis information may be exposed in plain text to any user or system that has HTTP access to the Monitor Agent API.\n\n### Impact\nThis vulnerability allows for unauthorized information disclosure. An attacker who can reach the Monitor Agent API port (default: `24220`) can potentially extract sensitive credentials used by other Fluentd plugins.\nThe impact severity depends highly on the network configuration (whether the Monitor Agent port is exposed to untrusted networks) and the specific plugins configured in the Fluentd instance.\n\n### Patches:\nv1.19.3\n\n### Workarounds\nIf usesrs cannot immediately update Fluentd to the patched version, they can mitigate this risk by strictly controlling access to the Monitor Agent port.\n\nEnsure the Monitor Agent is only bound to `localhost` (`127.0.0.1`) rather than `0.0.0.0`.\n\n```\n<source>\n  @type monitor_agent\n  bind 127.0.0.1\n  port 24220\n</source>\n```\n\nUse firewall rules (e.g., iptables, AWS Security Groups) to block access to the Monitor Agent port (`24220`) from untrusted networks or instances.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "fluentd"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.19.3"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.19.2"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/fluent/fluentd/security/advisories/GHSA-pr7j-96cj-549h"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/fluent/fluentd"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fluent/fluentd/releases/tag/v1.19.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-306" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-26T16:32:57Z",
    "nvd_published_at" : null
  }
}