CVE-2026-40586 in blueprintue-self-hosted-edition
Summary
by MITRE • 04/21/2026
blueprintUE is a tool to help Unreal Engine developers. Prior to 4.2.0, the login form handler performs no throttling of any kind. Failed authentication attempts are processed at full network speed with no IP-based rate limiting, no per-account attempt counter, no temporary lockout, no progressive delay (Tarpit), and no CAPTCHA challenge. An attacker can submit an unlimited number of credential guesses. The password policy (10+ characters, mixed case, digit, special character) reduces the effective keyspace but does not prevent dictionary attacks, credential stuffing from breached databases, or targeted attacks against known users with predictable passwords. This vulnerability is fixed in 4.2.0.
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Analysis
by VulDB Data Team • 07/04/2026
The blueprintUE tool represents a significant security weakness in Unreal Engine development environments through its inadequate authentication handling mechanisms. The absence of any form of rate limiting or account protection measures creates an exploitable condition that fundamentally undermines the security posture of the development infrastructure. This vulnerability exists at the core of the login form handler implementation where no defensive controls are implemented to prevent automated credential guessing attacks.
The technical flaw manifests as a complete lack of authentication throttling mechanisms that should be standard in any security-conscious application. Without IP-based rate limiting, attackers can submit unlimited authentication requests without facing any network-level restrictions or delays that would normally slow down automated attack vectors. The system fails to implement per-account attempt counters that would track failed login attempts and trigger protective measures once a threshold is exceeded. Additionally, the absence of temporary lockout mechanisms means that even after multiple failed attempts, the account remains vulnerable to continued attack attempts without any form of account lock or temporary access restriction.
The operational impact of this vulnerability extends far beyond simple credential guessing attacks and creates conditions that enable sophisticated attack patterns including dictionary attacks, credential stuffing operations, and targeted assaults against specific user accounts. The reduced effective keyspace resulting from the password policy requirements does not provide meaningful protection since attackers can leverage breached databases containing previously compromised credentials to conduct successful attacks. This vulnerability allows for rapid exploitation through automated tools that can test thousands of credential combinations per minute without any throttling interference.
The security implications align with common attack patterns documented in the attack framework where adversaries exploit weak authentication controls to gain unauthorized access to development environments. The lack of progressive delay mechanisms or tarpitting techniques removes any form of network-level obfuscation that would make automated attacks more resource-intensive and time-consuming. Without CAPTCHA challenges or additional verification mechanisms, the system provides no barriers for automated attack tools to systematically test credentials against valid accounts.
This vulnerability directly corresponds to well-established security weaknesses identified in industry standards such as CWE-307, which addresses inadequate account lockout mechanisms and insufficient authentication throttling. The implementation fails to adhere to fundamental security principles that require rate limiting and authentication attempt monitoring as basic protective measures. Organizations using blueprintUE versions prior to 4.2.0 face significant risk of unauthorized access to their development environments, potentially leading to code injection attacks, intellectual property theft, or compromise of sensitive development data.
The mitigation strategy requires immediate upgrading to version 4.2.0 or later where the authentication throttling mechanisms have been properly implemented and configured. Security teams should also consider implementing additional protective measures such as network-level rate limiting, enhanced monitoring for unusual authentication patterns, and regular security assessments of development environments to identify similar vulnerabilities in other tools or systems that may not have received proper security updates.
The fix implemented in version 4.2.0 addresses the fundamental design flaw by introducing comprehensive rate limiting controls and authentication attempt monitoring that prevents the types of attacks described in this vulnerability analysis. This represents a critical improvement in the tool's security posture and aligns with established security best practices for protecting authentication systems from automated attack vectors. Organizations should verify that their blueprintUE installations have been properly updated to ensure complete protection against credential-based attacks and maintain ongoing security monitoring to detect any potential exploitation attempts.