CVE-2026-44024
Description
A flaw was found in Fluentd, a data collector. This vulnerability allows a remote attacker to achieve arbitrary file write and potentially remote code execution by sending untrusted tags containing path traversal characters. The issue arises from insufficient validation of the ${tag} placeholder in file configurations, such as the path parameter of the out_file plugin. Successful exploitation could lead to a full system compromise without authentication, depending on the Fluentd configuration and its process privileges.
Statement
Red Hat has determined that no Red Hat product is currently affected by this vulnerability. Exploitation requires a Fluentd deployment configured with an output plugin, such as out_file, that constructs file paths dynamically from the ${tag} placeholder, combined with the ability for an attacker to submit untrusted, attacker-influenced tags to that Fluentd instance (for example, via an exposed forward or HTTP input). Deployments that do not accept externally influenced tags, or that do not use tag-based dynamic path construction in output plugin configuration, are not exposed to this issue in practice. Red Hat has completed a portfolio-wide search for Fluentd across Red Hat product offerings (strict and substring dependency search) and found no currently supported Red Hat product that ships the vulnerable code path.
Mitigation
Upgrade to Fluentd 1.19.3 or later, which validates the ${tag} placeholder in output plugin path configuration and rejects path traversal characters. Where an immediate upgrade is not possible: avoid using the ${tag} placeholder in file-path-based output plugin configuration (such as the path parameter of out_file); if dynamic tag-based paths are required, restrict allowed tag values with an explicit allowlist/regex filter (for example via a <filter> directive) before they reach the output plugin; and ensure only trusted sources can submit tags to the Fluentd instance by not exposing its forward or HTTP input directly to untrusted networks.
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
The attacker may be able to create or overwrite critical files that are used to execute code, such as programs or libraries.
Integrity
Technical Impact: Modify Files or Directories
The attacker may be able to overwrite or create critical files, such as programs, libraries, or important data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, appending a new account at the end of a password file may allow an attacker to bypass authentication.
Confidentiality
Technical Impact: Read Files or Directories
The attacker may be able read the contents of unexpected files and expose sensitive data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, by reading a password file, the attacker could conduct brute force password guessing attacks in order to break into an account on the system.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The attacker may be able to overwrite, delete, or corrupt unexpected critical files such as programs, libraries, or important data. This may prevent the product from working at all and in the case of protection mechanisms such as authentication, it has the potential to lock out product users.
Frequently Asked Questions
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