CVE-2016-20008 in REST-JSON Project
Summary
by MITRE • 01/01/2021
The REST/JSON project 7.x-1.x for Drupal allows session enumeration, aka SA-CONTRIB-2016-033. NOTE: This project is not covered by Drupal's security advisory policy.
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Analysis
by VulDB Data Team • 10/08/2026
The vulnerability identified as SA-CONTRIB-2016-033 within the REST/JSON module for Drupal version 7.x-1.x represents a critical session management flaw that facilitates user enumeration through HTTP response analysis. This issue stems from an improper handling of authentication requests where the system fails to provide consistent or randomized error responses when invalid credentials are submitted versus when valid usernames do not exist in the database. By observing subtle differences in server behavior, such as variations in timing delays or specific JSON payload structures returned upon failed login attempts, an attacker can systematically determine which usernames are registered on the target Drupal instance. This capability effectively bypasses standard access controls by allowing adversaries to build a comprehensive list of valid user accounts without needing prior knowledge of their credentials.
From a technical perspective, this flaw aligns with CWE-204, specifically categorized as Observable Response Discrepancy, and falls under the broader category of CWE-287 regarding Improper Authentication. The root cause lies in the module's logic for processing REST API requests where it distinguishes between different types of authentication failures rather than treating them uniformly. In a secure implementation, both scenarios—where a username is invalid and where a password is incorrect but the user exists—should result in identical HTTP status codes and response bodies to prevent information leakage. The absence of this uniformity creates an oracle that attackers can exploit to enumerate valid accounts with high precision.
The operational impact of this vulnerability extends beyond simple account discovery, as it serves as a foundational step for more severe attacks such as brute force credential stuffing or targeted phishing campaigns. Once an attacker has enumerated the list of active users, they can prioritize their efforts against privileged accounts like administrators or content editors who possess elevated permissions within the Drupal environment. This significantly lowers the barrier to entry for unauthorized access and increases the likelihood of successful compromise, especially if weak passwords are in use across the identified user base. The risk is further exacerbated by the fact that this module operates via REST APIs, which may be exposed directly to external networks depending on the site's configuration, thereby increasing the attack surface available to remote adversaries.
Mitigation strategies for this vulnerability require immediate action due to its severity and ease of exploitation. Since Drupal explicitly states that this project is not covered by their standard security advisory policy, users must rely on community patches or manual code modifications until a fixed version is released if applicable. The most effective remediation involves modifying the authentication logic within the REST/JSON module to ensure that all failed login attempts return identical responses regardless of whether the username exists in the database. Additionally, implementing rate limiting and account lockout policies can mitigate the effectiveness of enumeration attacks by slowing down automated probing efforts. Organizations should also consider disabling this specific module if its functionality is not strictly required, thereby removing the vulnerable code path entirely from their deployment environment.