FluentdApplication

CVE-2026-44024

CRITICAL · 9.8 CVSS v3.1 Published 2026-07-08
Fix available
A fix is available. Upgrade to 1.19.3 or later.
See remediation →
100/100
Remediation priority · Urgent
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, Fluentd allows dynamically constructing file paths using the ${tag} placeholder, and insufficient validation of ${tag} in file configurations such as the path parameter of the out_file plugin allows attackers sending untrusted tags containing path traversal characters to write or overwrite arbitrary files and potentially achieve remote code execution. This issue is fixed in version 1.19.3.

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Third-party coverage
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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 · moderate confidence

Fluentd's out_file plugin allows dynamic file path construction using the ${tag} placeholder. Due to insufficient validation of user-controlled tag values, attackers can inject path traversal sequences (e.g., ../../) in tags to write or overwrite arbitrary files on the Fluentd host, potentially achieving remote code execution.

MitigationUpgrade Fluentd to version 1.19.3 or later. Additionally, implement input validation on incoming tags to reject path traversal characters before processing.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Fluentd version
    Run 'fluentd --version' or check the installed gem version with 'gem list fluentd'
    Affected if The installed version is below 1.19.3
  2. Locate Fluentd configuration files
    Search for *.conf files in typical locations such as /etc/fluent/, /etc/, or the working directory. Look for files containing 'out_file' plugin directives.
    Affected if out_file plugin is configured and in use
  3. Inspect out_file path configuration
    Examine the out_file configuration block and identify if the <file> path parameter contains the ${tag} placeholder (for example, 'path /var/log/fluent/myapp.${tag}.log')
    Affected if The path parameter uses ${tag} without additional sanitization of tag values
  4. Check for tag input sources
    Review all input plugin configurations (such as in_forward, syslog, tail) that produce the tags fed to out_file. Identify whether external or untrusted sources can influence tag values.
    Affected if Tags are derived from untrusted external sources without validation
  5. Review logs for path traversal indicators
    Examine Fluentd logs for patterns like '../' in tag-related error messages or unexpected file paths. Also check for files created outside the intended directory.
    Affected if Log entries or created files show evidence of path traversal sequences in tags

A defender is affected if Fluentd version is below 1.19.3 AND the out_file plugin is configured with a ${tag} placeholder in the path parameter, with tags originating from untrusted sources.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 →
Interim mitigation

Upgrade Fluentd to version 1.19.3 or later. Additionally, implement input validation on incoming tags to reject path traversal characters before processing.

Recommended fix High confidence

Fluentd 1.19.3

  1. Check current Fluentd version using 'fluentd --version' or check the Gemfile/gem lockfile
  2. Upgrade Fluentd to version 1.19.3 or later by running 'gem install fluentd -v 1.19.3' or updating the version in your Gemfile
  3. Restart the Fluentd service to apply the updated version
  4. Verify the upgrade was successful by checking 'fluentd --version' shows 1.19.3 or higher
  5. Review any out_file plugin configurations that use the ${tag} placeholder in the path parameter to ensure proper validation is now applied
Caveat No breaking changes documented for this security patch; standard upgrade testing recommended

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

Fix this in Fluentd Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2026-44024 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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