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FluentdApplication

CVE-2026-44161

HIGH · 7.2 CVSS v3.1 Published 2026-07-08
Fix available
A fix is available. Upgrade to 1.19.3 or later.
See remediation →
81/100
Remediation priority · High
Remotely reachable No privileges Zero-click Patch available 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-918

The server can be induced to make requests to a URL an attacker controls, turning it into a proxy into internal networks and cloud metadata services. It's especially dangerous behind a trusted network boundary. The fix is strict allow-listing of destinations and blocking access to internal address ranges.

General guidance for the server-side request forgery (ssrf) class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FluentdApplication
Affected:< 1.19.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
Low

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.19.3 or later
Fixed in 1.19.3
Vendor patch github.com →
Recommended fix High confidence

Fluentd 1.19.3

  1. 1. Identify all Fluentd instances running version < 1.19.3 in your environment
  2. 2. Review configurations using the out_http output plugin to identify if endpoint parameters use ${tag} or other placeholders that could be derived from untrusted input
  3. 3. If using package managers (gem, apt, yum, etc.), upgrade Fluentd to version 1.19.3 or later
  4. 4. If using Bundler, update the Gemfile with `gem 'fluentd', '~> 1.19.3'` and run `bundle update fluentd`
  5. 5. If running from source, pull the latest code or checkout tag v1.19.3 and reinstall
  6. 6. Verify the installed version using `fluentd --version` or `gem list fluentd`
  7. 7. Restart the Fluentd service to load the new version
  8. 8. Validate that the out_http plugin configuration does not allow untrusted input to control placeholder values in the endpoint parameter
Caveat Review custom configurations for out_http plugin as behavior may have changed; test thoroughly in staging before production deployment

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-44161 in production — separate from our analysis above.

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What this is

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