# CVE-2026-44161: Fluent Fluentd SSRF in out_http output plugin

Source: https://junglewise.ai/threats/cve-2026-44161-fluent-fluentd-ssrf-in-out-http-output-plugin  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-08. Updated: 2026-07-08  
License: CC BY 4.0 with a link back

CVE-2026-44161 · Severity: high · CVSS 7.2 · Published 2026-07-08

Fluentd is a popular data collection tool used to gather logs and events from various sources and send them to storage or analysis platforms. A security flaw in its HTTP output plugin allows attackers to manipulate where these logs are sent by injecting malicious data into event tags. This could allow an attacker to bypass network security controls and force the server to send requests to internal systems, potentially exposing sensitive internal data or cloud metadata.

Technologies: [fluentd (RubyGems)](https://junglewise.ai/threats/technologies/fluentd). Vendors: [RubyGems](https://junglewise.ai/threats/vendors/rubygems).

## Quick answers

**Is CVE-2026-44161 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44161 being exploited in the wild.

**How severe is CVE-2026-44161?** High severity, with a CVSS score of 7.2, published 8 July 2026.

**Which products and versions are affected?** fluentd (RubyGems) <= 1.19.2, ECOSYSTEM:introduced=0,fixed=1.19.3.

**Is there a fix for CVE-2026-44161?** Yes. fluentd (RubyGems): upgrade to 1.19.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44161 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-44161?** Check whether you run fluentd (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- fluentd (RubyGems): upgrade to 1.19.3 or later

  ```sh
  bundle update fluentd
  ```


## Technical details

A Server-Side Request Forgery (SSRF) vulnerability exists in Fluentd's 'out_http' output plugin due to insufficient validation of dynamic placeholders (e.g., ${tag}) in the endpoint configuration. If a placeholder value is derived from untrusted input, a remote attacker can manipulate the destination hostname of outbound HTTP requests. This allows the attacker to force Fluentd to send POST or PUT requests to arbitrary internal services or cloud metadata endpoints (like AWS IMDS). The vulnerability is addressed in version 1.19.3 by introducing strict host validation and a new 'allowed_hosts' parameter to explicitly define permitted destination hostnames.

## Affected products

- Fluent Fluentd < 1.19.3

## Identifiers

- CVE-2026-44161
- GHSA-72f5-rr8c-r6gr

## Timeline

- 2026-06-25: patched: Fix merged into v1.19 branch and version 1.19.3 released.
- 2026-06-26: advisory: GitHub Security Advisory GHSA-72f5-rr8c-r6gr published.
- 2026-07-08: disclosed: CVE-2026-44161 published to NVD.

## References

- [https://github.com/fluent/fluentd/commit/c6a01ea2e0ea01977f8d615f7c6dbfae4cba88c9](https://github.com/fluent/fluentd/commit/c6a01ea2e0ea01977f8d615f7c6dbfae4cba88c9)
- [https://github.com/fluent/fluentd/pull/5394](https://github.com/fluent/fluentd/pull/5394)
- [https://github.com/fluent/fluentd/releases/tag/v1.19.3](https://github.com/fluent/fluentd/releases/tag/v1.19.3)
- [https://github.com/fluent/fluentd/security/advisories/GHSA-72f5-rr8c-r6gr](https://github.com/fluent/fluentd/security/advisories/GHSA-72f5-rr8c-r6gr)

## Related threats

- [Fluent Fluentd denial of service via decompression bomb in input plugins](https://junglewise.ai/threats/cve-2026-44160-fluent-fluentd-denial-of-service-via-decompression-bomb-in-input)
- [Fluent Fluentd information disclosure in Monitor Agent plugin](https://junglewise.ai/threats/cve-2026-44025-fluent-fluentd-information-disclosure-in-monitor-agent-plugin)
- [Fluent Fluentd path traversal in ${tag} placeholder](https://junglewise.ai/threats/cve-2026-44024-fluent-fluentd-path-traversal-in-tag-placeholder)
- [fluentd vulnerable to remote code execution due to insecure deserialization (in non-default configuration)](https://junglewise.ai/threats/cve-2022-39379-fluentd-vulnerable-to-remote-code-execution-due-to-insecure)
- [Fluentd Escape Sequence Injection Vulnerability](https://junglewise.ai/threats/cve-2017-10906-fluentd-escape-sequence-injection-vulnerability)