CVE-2025-15490 in Passster Plugin
Summary
by MITRE • 09/02/2026
The Passster WordPress plugin before 4.2.26 has a flaw in its global protection checks, allowing unauthenticated users to bypass the protection offered via crafted URLs
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Analysis
by VulDB Data Team • 09/02/2026
The vulnerability identified in versions of the Passster WordPress plugin prior to release 4.2.26 represents a critical authentication bypass mechanism rooted in flawed input validation logic within the application's core security controls. This flaw specifically targets the global protection checks that are designed to restrict access to password-protected content or administrative areas, ensuring that only authorized users with valid credentials can interact with sensitive resources. The root cause lies in an insufficient verification process where the plugin fails to rigorously validate the integrity and authenticity of incoming URL parameters before granting access. By crafting specific URLs that exploit this logical gap, unauthenticated attackers can circumvent the intended security barriers without possessing any legitimate user credentials or passwords.
From a technical perspective, this vulnerability is classified under CWE-287, which denotes Improper Authentication, as well as CWE-306, Missing Authentication for Critical Function, depending on the specific context of the protected resource. The exploitation vector relies on manipulating query strings or path structures to trick the application into skipping critical authentication checks. This type of flaw is often associated with ATT&CK technique T1528, Steal Application Access Token, although in this case, it allows direct access without needing a token initially, effectively bypassing the initial gatekeeping mechanism entirely. The attacker constructs URLs that appear legitimate to the application's routing logic but lack the necessary cryptographic or session-based proofs required for authorized access, thereby tricking the server into serving protected content directly to an anonymous visitor.
The operational impact of this vulnerability is severe, particularly in environments where Passster is used to protect sensitive documents, private user profiles, or restricted administrative sections. Successful exploitation allows unauthenticated users to view confidential information that was intended to be hidden behind a password wall. This can lead to significant data exposure, including personal identifiable information (PII), proprietary business data, or internal system configurations. Furthermore, if the protected content includes links to further vulnerabilities or sensitive endpoints, this bypass serves as an initial foothold for more advanced attacks such as credential stuffing or privilege escalation. The lack of authentication means that any user on the internet can potentially access these resources, leading to a complete compromise of confidentiality and integrity for the affected data sets.
Mitigation strategies must focus on immediate remediation through software updates and enhanced input validation practices. Administrators running vulnerable versions should upgrade immediately to version 4.2.26 or later, where this logic flaw has been corrected by implementing stricter checks on URL parameters and ensuring that authentication tokens are validated against every request regardless of the entry point. In addition to patching, it is advisable to implement Web Application Firewall (WAF) rules that detect anomalous URL patterns indicative of bypass attempts. Regular security audits focusing on access control logic and adherence to OWASP guidelines for authentication mechanisms will help prevent similar vulnerabilities in future development cycles. Ensuring that all protected resources require explicit verification of user identity before rendering content is essential to maintaining the integrity of the application's security posture.