CVE-2025-66203: A Critical Remote Code Execution Flaw in StreamVault

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CVE : CVE-2025-66203
Published Date:12/26/2025
Last Modified:12/26/2025

CVE-2025-66203 is a recently disclosed critical security vulnerability affecting StreamVault, a video download integration solution used in applications that rely on yt-dlp tooling for media retrieval and processing. The vulnerability was publicly registered on December 26, 2025, and has attracted attention due to its severity and potential impact on systems that expose administrative configuration interfaces.

What Is the Vulnerability?

At its core, CVE-2025-66203 is a Remote Code Execution (RCE) vulnerability caused by improper input validation in how StreamVault handles command-line arguments for the yt-dlp utility:

  • The affected component is the /admin/api/saveConfig endpoint in StreamVault’s SpiritApplication.
  • This API endpoint allows administrators to configure arguments that control how yt-dlp is executed internally.
  • However, the endpoint does not sufficiently validate these arguments before storing them.
  • Later, these stored arguments are passed unchecked to the YtDlpUtil.java component, which builds and executes a command line to run yt-dlp.
  • Because of the lack of sanitization, a malicious or misused configuration can inject special characters or constructs that allow an attacker to execute arbitrary OS commands.

This type of vulnerability maps to CWE-78: Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’), a common class of flaw where untrusted input alters the logic or intent of executed commands.

Severity and Scoring

Although the official NVD assessment has not yet provided its own CVSS score, the project that originally reported the issue — StreamVault’s maintainers, via GitHub’s security advisory — assigned it a CVSS v3.1 base score of 9.9 (Critical). This reflects the following characteristics:

  • AV:N – Network-accessible attack vector
  • AC:L – Low attack complexity
  • PR:L – Requires some level of privileges (e.g., administrative access to configuration APIs)
  • UI:N – No user interaction required
  • C:H/I:H/A:H – High impact on confidentiality, integrity, and availability if exploited

A score this high indicates that, in the worst case, successful exploitation could lead to full system takeover, data compromise, or disruption of service.

Impact and Attack Scenarios

In typical deployments, StreamVault may run on servers that integrate media downloading capabilities into larger platforms. An attacker who can access the administrative configuration interface — or who obtains these privileges through other means — could:

  • Craft malicious yt-dlp argument strings that execute unintended commands on the host.
  • Escalate beyond normal functionality to read, modify, or delete data.
  • Deploy malware or backdoors with the privileges of the running service.
  • Interrupt normal service operations by triggering destructive commands.

Because the vulnerability stems from configuration misuse, its exploitability is closely tied to how access controls are enforced around the configuration endpoint. Without proper access restrictions, this flaw could be especially dangerous for systems exposed to untrusted networks.

Mitigation and Remediation

The maintainers of StreamVault have released a fix in version 251126 and later of the software. Systems still running earlier versions are considered vulnerable and are strongly advised to update to the patched release as soon as possible.

Mitigation Details

https://github.com/lemon8866/StreamVault/releases/tag/251226

https://github.com/lemon8866/StreamVault/security/advisories/GHSA-c747-q388-3v6m

Additional best practices include:

  • Restricting access to administrative interfaces behind strong authentication and network controls.
  • Validating and sanitizing all inputs, even from administrators, before using them in command execution.
  • Implementing role-based access control so only trusted users can configure internal tooling parameters.

Why This Matters

Remote command execution vulnerabilities like CVE-2025-66203 continue to be among the most dangerous security issues because they directly give an attacker the ability to run arbitrary code on a target system. Even when limited by authentication requirements, misconfigurations or credential compromise can turn them into a full takeover risk.

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