GHSA-pr7j-96cj-549h BIT-fluentd-2026-44025 CVE-2026-44025

Fluentd is Vulnerable to Exposure of Sensitive Information via Monitor Agent API

High RubyGems

Severity: 7.5 / 10; High · CVSS 3.1
Exploit chance (EPSS): 0.47%; Chance of exploitation in the next 30 days. Higher than 41.01% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-200 Exposure of Sensitive Information to an Unauthorized Actor; CWE-306 Missing Authentication for Critical Function
Fix: 1.19.3; Upgrade fluentd to this version or later

Description

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.

Affected versions

RubyGems

Package	Vulnerable	Fixed in
fluentd	`< 1.19.3`	`1.19.3`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

fluentd RubyGems → `1.19.3`

bundler

bundle update fluentd # Gemfile: gem "fluentd", ">= 1.19.3"

Severity breakdown

CVSS 3.1 7.5

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

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Weakness

CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

How to prevent it

Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

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 to prevent it

Architecture and Design: Divide the software into anonymous, normal, privileged, and administrative areas. Identify which of these areas require a proven user identity, and use a centralized authentication capability. Identify all potential communication channels, or other means of interaction with the software, to ensure that all channels are appropriately protected, including those channels that are assumed to be accessible only by authorized parties. Developers sometimes perform authentication at the primary channel, but open up a secondary channel that is assumed to be private. For example, a login mechanism may be listening on one network port, but after successful authentication, it may open up a second port where it waits for the connection, but avoids authentication because it assumes that only the authenticated party will connect to the port. In general, if the software or protocol allows a single session or user state to persist across multiple connections or channels, authentication and appropriate credential management need to be used throughout.
Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Architecture and Design: Where possible, avoid implementing custom, "grow-your-own" authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment. These capabilities may avoid common weaknesses that are unique to authentication; support automatic auditing and tracking; and make it easier to provide a clear separation between authentication tasks and authorization tasks. In environments such as the World Wide Web, the line between authentication and authorization is sometimes blurred. If custom authentication routines are required instead of those provided by the server, then these routines must be applied to every single page, since these pages could be requested directly.
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator [REF-45].
Implementation, System Configuration, Operation: When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data [REF-1297] [REF-1298] [REF-1302].

References

Fixes and patches

Packages

github.com/fluent/fluentd

Timeline

Jun 26, 2026 Published
Oct 25, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-72f5-rr8c-r6gr Fluentd is Vulnerable to Server-Side Request Forgery (SSRF) via Placeholder Expansion in `out_http`	High	Also affects fluentd
GHSA-j9cw-hwqf-85w7 Fluentd is Vulnerable to Denial of Service (DoS) via Gzip Decompression Bomb in `in_http` and `in_forward`	High	Also affects fluentd
GHSA-44hj-4m45-frj3 Fluentd is Vulnerable to Remote Code Execution (RCE) via Arbitrary File Write in `${tag}` Placeholder	Critical	Also affects fluentd
GHSA-fppq-mj76-fpj2 fluentd vulnerable to remote code execution due to insecure deserialization (in non-default configuration)	Low	Also affects fluentd
GHSA-5jrp-w8fr-mrww Fluentd Escape Sequence Injection Vulnerability	Critical	Also affects fluentd
GHSA-hwhf-64mh-r662 ReDoS vulnerability in parser_apache2	Medium	Also affects fluentd
GHSA-j7qq-vr8c-xvw3 MLflow CrewAI autologging records LLM provider API keys in logged trace spans	Medium	Same weakness, CWE-200
GHSA-gqh3-7856-rjjg ApostropheCMS: :_id/locales REST route omits the public-API authorization gate its sibling read routes enforce (unauthenticated doc-existence + locale metadata disclosure)	Medium	Same weakness, CWE-200

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