Description

Unauthenticated Bypass Vulnerability in CAPTCHA 4WP <= 7.6.0 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.3",
  "pubDate": "2026-08-06T15:16:54.333Z",
  "pubdate": "2026-08-06T15:16:54.333Z",
  "executiveSummary": "An unauthenticated bypass vulnerability has been identified in the CAPTCHA 4WP plugin affecting versions 7.6.0 and below. This security flaw allows remote, unauthenticated attackers to completely circumvent the intended CAPTCHA validation mechanisms implemented by the plugin across protected forms and authentication endpoints.\nThe primary impact of this vulnerability is the breakdown of automated bot mitigation and defense controls designed to protect web applications against credential stuffing, automated brute-force attacks, and unauthorized form submissions. By successfully bypassing the validation check, malicious actors can interact with target endpoints as if a valid human user completed the challenge.\nThe affected system is the CAPTCHA 4WP WordPress plugin running versions 7.6.0 or earlier. The risk implication is severe for sites relying on the plugin to secure sensitive entry points such as login pages, registration forms, and password recovery mechanisms, as it exposes them directly to automated threats.\nExploitation requirements are minimal, as the vulnerability does not require any prior authentication, user interaction, or elevated privileges. An attacker with standard network access can exploit this flaw by manipulating requests directed at the vulnerable component, neutralizing the security controls provided by the software.",
  "technicalDetails": "The vulnerability resides within the request handling and validation logic of the CAPTCHA 4WP plugin for versions 7.6.0 and below. The root cause stems from improper input validation, weak session or token verification, or flawed conditional checks that determine whether a CAPTCHA challenge has been successfully solved before processing the underlying form submission or authentication request.\nBecause the validation mechanism fails to cryptographically bind the CAPTCHA resolution state to the specific request session or omits proper server-side verification of the response token, an attacker can manipulate or omit the expected CAPTCHA parameters. The vulnerable component accepts these crafted requests as valid, effectively bypassing the security gatekeeper without executing the verification logic against the third-party CAPTCHA provider API or internal validation routines.\nThe attack flow proceeds as follows: First, the attacker identifies a form protected by CAPTCHA 4WP, such as the WordPress login page or a user registration form. Second, instead of solving the visual or interactive challenge, the attacker constructs an HTTP POST or GET request directed at the target endpoint. Third, the attacker injects a manipulated payload, drops the CAPTCHA verification parameters entirely, or replays a previously captured state depending on the exact flaw in the validation logic. Fourth, the vulnerable component processes the request, incorrectly evaluates the missing or forged validation data as a successful challenge response, and permits the transaction to complete.\nNetwork exposure is remote, as the vulnerability can be exploited over the standard HTTP/HTTPS protocols via standard web browser requests or automated scripting tools. Authentication requirements are entirely absent, allowing unauthenticated threat actors to interact directly with the vulnerable endpoints. Privilege requirements are nonexistent, as no administrative or registered user account is needed to trigger the flaw.\nThe post-exploitation impact includes the automated execution of brute-force attacks against administrative accounts, mass automated spam generation, unauthorized resource consumption, and the potential circumvention of multi-layered defense-in-depth strategies that rely on CAPTCHA 4WP as a primary perimeter defense against non-human traffic."
}