External risk intelligence

OpenBullet2 API Key Authentication Bypass Allows Admin Access

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-25555

OpenBullet2 is a web-based testing and automation suite designed to be accessed via an admin console or API endpoints. Given its role as a web application and management service, it is commonly deployed as a network-reachable or internet-facing service to facilitate remote management and task execution.

Authentication Bypass

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability exists in OpenBullet2 that allows unauthorized access to administrative functions. This issue arises from how the system handles API key authentication, specifically when an empty API key is provided. The potential impact is that unauthenticated individuals could gain full control over the application's administrative console and all associated API endpoints.

Unauthenticated attackers can access admin controls.
Leadership should remember this bypass of core security.
Confirm relevance and exposure of this tool.

Attack Path

How an attacker could exploit the issue

An attacker could bypass authentication in OpenBullet2 by sending a request with an empty API key header. This could allow them to access administrative functions and all API endpoints, potentially leading to full system control.

Requires network access.
Empty API key header.
Unauthorized admin access.

Live Threat

Current exploitation, exposure, and threat context

An authentication bypass vulnerability in OpenBullet2's API key middleware could allow unauthenticated attackers to gain administrative access. This occurs when the system compares an empty `X-Api-Key` header to a default empty administrator API key, granting unauthorized access to the admin console and all API endpoints.

Admin console and API endpoints.
Empty API key header bypass.
Unauthorized administrative access.

Operational Fix

Recommended remediation, mitigation, and detection steps

The OpenBullet2 authentication bypass vulnerability likely impacts teams responsible for managing web applications and their APIs. The first practical step is to locate all instances of OpenBullet2, assess their exposure and criticality, and identify the accountable owners. Remediation efforts should then be prioritized based on this risk assessment.

Application owners should verify asset inventory.
Confirm external reachability and critical systems.
Plan vendor coordination for patching.

Supplementary metadata

CVSS vector

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Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is OpenBullet2?

OpenBullet2 is a web-based software suite used for automated testing and data processing tasks. It provides users with an administrative console and API endpoints to manage workflows and execute operations. Because it is designed for remote task management, it is typically deployed as a network-accessible service to allow users to control these functions from different locations.

What does CWE-305 mean for CVE-2026-25555?

CWE-305 refers to authentication bypass via an authentication-related weakness. In the context of CVE-2026-25555, the software's API key middleware is designed to verify requests. The flaw occurs because the system mistakenly accepts an empty header value as a valid credential, allowing unauthorized users to circumvent login protections and gain full administrative privileges.

How does an attacker trigger this authentication bypass?

An attacker triggers this flaw by sending a network request to the application with an empty 'X-Api-Key' header. The middleware performs a comparison between this empty input and a default empty administrator key value, resulting in a match. If an attacker provides a valid API key, the bug is not triggered, as the system successfully validates that specific credential instead of falling back to the vulnerable empty default.

Is my instance of OpenBullet2 at risk?

Your risk depends on how the software is deployed and accessed. According to Halo Surface Signal, OpenBullet2 is commonly set up as an internet-facing or network-reachable service to enable remote management. If your instance is accessible over the internet or reachable by untrusted users on your network, it is exposed to this bypass attempt.

How should I respond to this vulnerability?

Start by identifying every instance of OpenBullet2 running in your environment to understand your total footprint. Once you have a complete inventory, determine which instances are reachable over the network. Coordinate with your team to prioritize these assets based on their criticality, and track the status of vendor updates to ensure affected systems receive the necessary security improvements.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.