Description

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

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.3",
  "pubDate": "2026-09-02T15:17:36.713Z",
  "pubdate": "2026-09-02T15:17:36.713Z",
  "executiveSummary": "The Passster WordPress plugin prior to version 4.2.26 contains a critical flaw in its global protection verification logic.\nThe vulnerability is classified as an authentication or protection bypass, stemming from improper validation of access control mechanisms.\nThis flaw allows unauthenticated remote attackers to circumvent password or access protection on restricted content by submitting specifically crafted URLs.\nSuccessful exploitation results in unauthorized access to protected site areas, potentially exposing sensitive information or restricted features that the plugin was intended to guard.\nThere are no specific privilege requirements for an attacker, as the flaw targets the gatekeeping mechanism itself.\nThe risk is significant due to the ease of exploitation, as no complex interaction is required beyond the manipulation of the request URL.\nThe vulnerability impacts all instances of the Passster plugin running versions below 4.2.26, necessitating an immediate update to ensure content integrity and access control enforcement.",
  "technicalDetails": "The vulnerability resides within the global protection checking mechanism of the Passster WordPress plugin. The root cause is an insecure implementation of the access control logic, which fails to correctly validate the state of protected resources when requests are processed.\nIn a standard deployment, the Passster plugin intercepts requests to protected posts or pages, verifying user authorization before serving the content. However, in affected versions, the plugin's internal logic can be circumvented via manipulation of request parameters.\nThe attack vector involves the use of crafted URLs that trigger the plugin's protection logic in a way that it inadvertently fails-open, or incorrectly determines that the current request has already been validated. By manipulating specific URL parameters, an attacker can bypass the password verification gate entirely.\nThe attack flow proceeds as follows: 1) The attacker identifies a target URL protected by the Passster plugin. 2) The attacker crafts a request by appending or modifying URL components that interfere with the plugin's identification of the resource's protection status. 3) The server-side request handler processes the modified URL. 4) Due to the flawed global check, the plugin logic returns a false positive regarding the user's authorization status. 5) The plugin subsequently permits access to the protected content without requiring the password or authentication token.\nThis vulnerability is an authentication bypass that can be triggered over the network without any prior interaction or administrative privileges. The flaw is not related to user-level permissions, but rather a structural failure in the plugin's ability to enforce access control policy across all global request contexts.\nThe impact of successful exploitation allows unauthorized users to read, view, or potentially interact with content that administrators intended to keep private. Because the bypass occurs at the application layer, standard WordPress permission checks may be ignored if the plugin is the primary handler for that specific resource protection.\nVersion 4.2.26 addresses this by refining the protection check mechanisms, ensuring that the integrity of access control is maintained regardless of URL parameters or request manipulation attempts."
}