Weakness (CWE)
CWE-204: Observable Response Discrepancy
The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.
How to prevent it (2 mitigations)
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Architecture and Design
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
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Implementation
Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
Source: MITRE CWE-204
182 results · Clear filters · Feed
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Medium 5.3
Rejetto HFS < 3.2.1 Username Enumeration via Login Response Differences
Rejetto HFS 3.0.0 through 3.2.0 returns observably different responses from its login endpoint depending on whether the submitted username exists. A remote unauthenticated attacker can use this to confirm valid account names, including the default admin accou…
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Medium 6.9
User Enumeration in MCO
MCO is vulnerable to User Enumeration through authentication-related functionalities. The application returns distinguishable responses for valid and invalid users during username reminder and password reset operations. An attacker can leverage these differen…
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Medium —
Pterodactyl Panel: Client email change endpoint allows enumeration of accounts in system
### Summary An unprotected user enumeration vulnerability exists in the account email update endpoint, allowing authenticated users to verify whether email addresses are registered on the panel through automated requests without rate limiting or CAPTCHA prote…
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Medium 5.3
Ghost: Member existence leak via magic link sign-in response
Ghost is a Node.js content management system. From 5.18.0 until 6.21.1, a discrepancy in responses from the members signin endpoints made it possible for an unauthenticated attacker to determine whether a given email address belongs to a registered member of …
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Medium 6.9
Vantage6: Set admin user and password from environment or configuration
vantage6 is an open-source infrastructure for privacy preserving analysis. Versions prior to 5.0.0 provide an initial user with username `root` and password `root`. This is not ideal because attackers know that almost all vantage6 servers have a user with use…
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Medium 6.3
FOSSBilling's password reset confirmation endpoint lacks rate limiting
FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the password reset confirmation endpoint `/client/reset-password-confirm/:hash` is handled by a non-API controller and is not covered by FOSSBilling's rate limite…
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Medium 5.3
FreeScout: User Account Enumeration via Password Reset Response Differentiation
FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to 1.8.219, the password reset endpoint returns visually distinct responses depending on whether the submitted email address belongs to an existing user account, allowing…
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Medium 5.3
AVideo CVE-2026-43881 incomplete fix - `objects/mention.json.php:17` is an unauthenticated user enumeration
WWBN AVideo is an open source video platform. In 29.0 and earlier, objects/mention.json.php has no User::loginCheck() or admin gate. It only has an entry guard: preg_match('/^@/', $_REQUEST['term']) and hard-coded rowCount=10. This enables unauthenticated use…
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Medium 5.3
Statamic: Email enumeration via forgot password endpoint
Statamic is a Laravel and Git powered content management system (CMS). Prior to 5.73.21 and 6.15.0, responses from the forgot password forms hinted at whether an account existed for a given email address. An unauthenticated attacker could use this to enumerat…
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Medium 5.3
Username Enumeration via Email OTP Flow in Multiple WSO2 Products Allows User Account Discovery
The check user account lock states feature within the email OTP flow fails to validate user input, allowing an attacker to infer the existence of registered user accounts. The discovery of valid usernames can increase the risk of brute-force and social engine…
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Medium —
Lemmy resend-verification endpoint exposes registered email addresses to unauthenticated users
## Summary The unauthenticated resend-verification endpoint returns different responses for registered and unregistered email addresses. A malicious third party can submit candidate addresses to `/api/v4/account/auth/resend_verification_email` and distinguish…
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Medium 5.3
Cisco Identity Services Engine Observable Response Discrepancy Vulnerability
A vulnerability in an identity management API endpoint of Cisco ISE could allow an unauthenticated, remote attacker to enumerate valid user accounts on an affected device. This vulnerability exists because error messages are observed when the affected API end…
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Medium 5.0
Vulnerability in the MySQL Shell product of Oracle MySQL (component: Shell: Core Client). Supported versions that are a…
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Medium 5.3
OpenAEV Vulnerable to Username/Email Enumeration Through Differential HTTP Responses in Password Reset API
OpenAEV is an open source platform allowing organizations to plan, schedule and conduct cyber adversary simulation campaign and tests. Starting in version 1.11.0 and prior to version 2.0.13, the /api/reset endpoint behaves differently depending on whether the…
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Medium 5.3
ChurchCRM: Username Enumeration via Differential Response in Public Login API
ChurchCRM is an open-source church management system. In versions prior to 7.2.0, the public API login endpoint (/api/public/user/login) returns distinguishable HTTP response codes based on whether a username exists: 404 for non-existent users and 401 for val…
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Medium 6.5
Information Disclosure vulnerability in SAP Human Capital Management for SAP S/4HANA
During authorization checks in SAP Human Capital Management for SAP S/4HANA, the system returns specific messages. Due to this, an authenticated user with low privileges could guess and enumerate the content shown, beyond their authorized scope. This leads to…
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Medium 5.3
Saleor has a user enumeration vulnerability due to different error messages
Saleor is an e-commerce platform. From 2.10.0 to before 3.23.0a3, 3.22.47, 3.21.54, and 3.20.118, the requestEmailChange() mutation was revealing the existence of user-provided email addresses in error messages. This vulnerability is fixed in 3.23.0a3, 3.22.4…
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Medium 4.7
The login mechanism of Sage DPW 2025_06_004 displays distinct responses for valid and invalid usernames, allowing enume…
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Medium 5.3
User enumeration in ESET Protect (on-prem)
User enumeration in ESET Protect (on-prem) via Response Timing.
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Medium 6.3
Parse Server: Email verification resend page leaks user existence
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.51 and 9.6.0-alpha.40, the Pages route and legacy PublicAPI route for resending email verification links return distinguishable respo…
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Medium 5.3
AVideo has Pre-Captcha User Enumeration and Account Status Disclosure in Password Recovery Endpoint
WWBN AVideo is an open source video platform. In versions up to and including 26.0, the password recovery endpoint at `objects/userRecoverPass.php` performs user existence and account status checks before validating the captcha. This allows an unauthenticated…
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Medium 6.3
Chamilo LMS: User enumeration vulnerability via response
Chamilo LMS is a learning management system. Prior to version 1.11.36, Chamilo is vulnerable to user enumeration with valid/invalid username. This issue has been patched in version 1.11.36.
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Medium 6.9
User enumeration in Raytha CMS
Raytha CMS is vulnerable to User Enumeration in password reset functionality. Difference in messages could allow an attacker to determine if the login is valid or not, enabling a brute force attack with valid logins. This issue was fixed in version 1.5.0.
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Medium 5.3
IBM Aspera Console Information Disclosure
IBM Aspera Console 3.3.0 through 3.4.8 could allow an attacker to enumerate usernames due to an observable response discrepancy.
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Medium 5.1
Username Enumeration Observable Response Discrepancy vulnerability has been discovered in OpenText™ Vertica.
Observable response discrepancy vulnerability in OpenText™ Vertica allows Password Brute Forcing. The vulnerability could lead to Password Brute Forcing in Vertica management console application.This issue affects Vertica: from 10.0 through 10.X, from 11.0 …
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Medium 6.3
Unauthenticated Host Enumeration via Observable Response Discrepancy on Deploy Agent Endpoint
Improper permission enforcement in Checkmk versions 2.4.0 before 2.4.0p23, 2.3.0 before 2.3.0p43, and 2.2.0 (EOL) allows unauthenticated users to enumerate existing hosts by observing different HTTP response codes in deploy_agent endpoint, which could lead to…
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Medium 5.3
Authenticated Host Enumeration via Observable Response Discrepancy on Agent Register Existing Endpoint
Improper permission enforcement in Checkmk versions 2.4.0 before 2.4.0p23, 2.3.0 before 2.3.0p43, and 2.2.0 (EOL) allows authenticated users to enumerate existing hosts by observing different HTTP response codes in agent-receiver/register_existing endpoint, w…
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Medium 6.3
Parse Server has user enumeration via email verification endpoint
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 8.6.34 and 9.6.0-alpha.8, the email verification endpoint (/verificationEmailRequest) returns distinct error responses depending on whether an ema…
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Medium 5.3
Shopware has user enumeration via distinct error codes on Store API login endpoint
Shopware is an open commerce platform. Prior to 6.7.8.1 and 6.6.10.15, the Store API login endpoint (POST /store-api/account/login) returns different error codes depending on whether the submitted email address belongs to a registered customer (CHECKOUT__CUST…
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Medium 5.5CVE-2026-28288 Scanner template
Dify has a user enumeration issue
Dify is an open-source LLM app development platform. Prior to 1.9.0, responses from the Dify API to existing and non-existent accounts differ, allowing an attacker to enumerate email addresses registered with Dify. Version 1.9.0 fixes the issue.
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Medium 5.3
Rucio WebUI has Username Enumeration via Login Error Message
Rucio is a software framework that provides functionality to organize, manage, and access large volumes of scientific data using customizable policies. Prior to versions 35.8.3, 38.5.4, and 39.3.1, the WebUI login endpoint returns distinct error messages depe…
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Medium 5.5CVE-2025-62512 Scanner template
Piwigo Vulnerable to User Enumeration via Password Reset Endpoint
Piwigo is an open source photo gallery application for the web. In version 15.5.0 and likely earlier 15.x releases, the password reset functionality in Piwigo allows an unauthenticated attacker to determine whether a given username or email address exists in …
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Medium 5.3
Static Web Server: Timing-Based Username Enumeration in Basic Authentication
Static Web Server (SWS) is a production-ready web server suitable for static web files or assets. In versions 2.1.0 through 2.40.1, a timing-based username enumeration vulnerability in Basic Authentication allows attackers to identify valid users by exploitin…
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Medium 5.3CVE-2026-26744 Public exploit
A user enumeration vulnerability exists in FormaLMS 4.1.18 and below in the password recovery functionality accessible …
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Medium 5.3
Dokuwiki 2018-04-22b - Username Enumeration
DokuWiki 2018-04-22b contains a username enumeration vulnerability in its password reset functionality that allows attackers to identify valid user accounts. Attackers can submit different usernames to the password reset endpoint and distinguish between exist…
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Medium 5.3
CI4MS Vulnerable to User Email Enumeration via Password Reset Flow
CI4MS is a CodeIgniter 4-based CMS skeleton that delivers a production-ready, modular architecture with RBAC authorization and theme support. Prior to version 0.28.5.0, the authentication implementation in CI4MS is vulnerable to email enumeration. An unauthen…
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Medium 5.3
Open eClass is Vulnerable to Username Enumeration via Login Response Discrepancies
The Open eClass platform (formerly known as GUnet eClass) is a complete course management system. Prior to version 4.2, a username enumeration vulnerability allows unauthenticated attackers to identify valid user accounts by analyzing differences in the login…
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Medium 4.3CVE-2026-24332 Public exploit
Discord through 2026-01-16 allows gathering information about whether a user's client state is Invisible (and not actua…
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Medium 5.3
ZITADEL has a user enumeration vulnerability in Login UIs
ZITADEL is an open source identity management platform. Prior to 4.9.1 and 3.4.6, a user enumeration vulnerability has been discovered in Zitadel's login interfaces. An unauthenticated attacker can exploit this flaw to confirm the existence of valid user acco…
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Medium 5.3CVE-2026-21484 Scanner template
AnythingLLM Vulnerable to Username Enumeration w/ Password Recovery
AnythingLLM is an application that turns pieces of content into context that any LLM can use as references during chatting. Prior to commit e287fab56089cf8fcea9ba579a3ecdeca0daa313, the password recovery endpoint returns different error messages depending on …