Description

Packer up to 1.15.4 is vulnerable to an issue in the third-party plugin installer that may allow unintended file system modification and could lead to code execution. A user who installs a plugin from a malicious or compromised source may be affected. This vulnerability (CVE-2026-19589) is fixed in Packer 1.16.0.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-08-17T21:16:43.593Z",
  "pubdate": "2026-08-17T21:16:43.593Z",
  "executiveSummary": "HashiCorp Packer up to version 1.15.4 contains a security vulnerability within its third-party plugin installer mechanism. This flaw permits unintended file system modification operations, which can consequently facilitate arbitrary code execution on the host system. The vulnerability directly affects users who procure and install third-party plugins originating from malicious or otherwise compromised distribution channels.\nThe risk implications are severe, as successful exploitation enables an unauthorized actor to manipulate critical file system paths during the installation lifecycle. This capability transitions rapidly from unauthorized file modification to full code execution under the security context of the executing user. Prerequisites for successful exploitation involve user interaction, specifically the deliberate installation of a crafted plugin derived from a hostile or untrusted source.\nMitigation requires immediate administrative action to remediate the vulnerable software instances. Organizations and individual operators must upgrade the affected Packer deployments to version 1.16.0 or later, where the upstream vendor has applied the definitive security fix to resolve the improper file handling behavior within the plugin installation subsystem.",
  "technicalDetails": "The vulnerability resides within the third-party plugin installer component of Packer up to version 1.15.4. The root cause stems from insufficient validation and sanitization of file paths processed during the extraction or placement of downloaded plugin binaries and associated assets. When Packer retrieves and installs a plugin package, the installer routine fails to properly enforce boundary checks against the designated target installation directory.\nThe attack flow initiates when an attacker crafts a malicious plugin archive containing directory traversal sequences or absolute paths within its internal file structures. An unsuspecting user invokes the Packer plugin installation command, targeting the hostile plugin source or a compromised repository. Upon ingestion, the vulnerable installer parses the malicious archive without adequate containment validation.\nAs the installation routine executes, the lack of robust input sanitization allows the crafted file payloads to write, overwrite, or modify arbitrary files across the underlying host file system, extending beyond the intended plugin repository boundaries. By strategically targeting executable search paths, configuration files, or runtime dependencies, the persistent file modification primitives escalate into arbitrary code execution. This code executes with the access privileges of the local user running the Packer CLI session.\nAuthentication and privilege requirements for the attack are minimal regarding network access, as the vector relies entirely upon the local execution context triggered by the user. However, successful payload delivery requires external compromise or malicious creation of the third-party plugin package itself. The vulnerability affects all operating systems running Packer versions up to 1.15.4 where third-party plugin installation routines are invoked."
}