Observable discrepancies in the login process allow an attacker to guess legitimate user names registered in the BMC. This issue affects: Lanner Inc IAC-AST2500A standard firmware version 1.10.0.

Thinfinity VirtualUI before 3.0 allows a malicious actor to enumerate users registered in the OS (Windows) through the /changePassword URI. By accessing the vector, an attacker can determine if a username exists thanks to the message returned; it can be presented in different languages according to the configuration of VirtualUI. Common users are administrator, admin, guest and krgtbt.

In Cibele Thinfinity VirtualUI before 3.0, /changePassword returns different responses for invalid authentication requests depending on whether the username exists.

Omnissa Workspace ONE UEM contains an observable response discrepancy vulnerability. A malicious actor may be able to enumerate sensitive information such as tenant ID and user accounts that could facilitate brute-force, password-spraying or credential-stuffing attacks.

Dalmark Systems Systeam 2.22.8 build 1724 is vulnerable to User enumeration. The Systeam application is an ERP system that uses a mixed architecture based on SaaS tenant and user management, and on-premise database and web application counterparts. This issue occurs during the identification of the correct tenant for a given user, where a difference in messages could allow an attacker to determine if the given user is valid or not, enabling a brute force attack with valid users.

A vulnerability in the login functionality of the web application of ctrlX OS allows a remote unauthenticated attacker to guess valid usernames via multiple crafted HTTP requests.

Umbraco is a free and open source .NET content management system. Starting in version 14.0.0 and prior to versions 14.3.2 and 15.1.2, it's possible to determine whether an account exists based on an analysis of response codes and timing of Umbraco management API responses. Versions 14.3.2 and 15.1.2 contain a patch. No known workarounds are available.

IBM Cognos Controller 10.4.1, 10.4.2, and 11.0.0 could allow a remote user to enumerate usernames due to differentiating error messages on existing usernames. IBM X-Force ID: 199181.

A vulnerability in the External Interface of OTRS allows conclusions to be drawn about the existence of user accounts through different HTTP response codes and messages. This enables an attacker to systematically identify valid email addresses. This issue affects: * OTRS 7.0.X * OTRS 8.0.X * OTRS 2023.X * OTRS 2024.X * OTRS 2025.X

ManageEngine ADSelfService Plus below build 6116 contains an observable response discrepancy in the UMCP operation of the ChangePasswordAPI. This allows an unauthenticated remote attacker to determine whether a Windows domain user exists.

SAP NetWeaver Server ABAP allows an unauthenticated attacker to exploit a vulnerability that causes the server to respond differently based on the existence of a specified user, potentially revealing sensitive information. This issue does not enable data modification and has no impact on server availability.

An exposure of sensitive information vulnerability exists in TCExam <= 14.8.1. If a password reset request was made for an email address that was not registered with a user then we would be presented with an ‘unknown email’ error. If an email is given that is registered with a user then this error will not appear. A malicious actor could abuse this to enumerate the email addresses of

Directus is a real-time API and App dashboard for managing SQL database content. Before 11.14.1, a timing-based user enumeration vulnerability exists in the password reset functionality. When an invalid reset_url parameter is provided, the response time differs by approximately 500ms between existing and non-existing users, enabling reliable user enumeration. This vulnerability is fixed in 11.14.1.

In the Voatz application 2020-01-01 for Android, the amount of data transmitted during a single voter's vote depends on the different lengths of the metadata across the available voting choices, which makes it easier for remote attackers to discover this voter's choice by sniffing the network. For example, a small amount of sniffed data may indicate that a vote was cast for the candidate with the least metadata. An active man-in-the-middle attacker can leverage this behavior to disrupt voters' abilities to vote for a candidate opposed by the attacker.

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 supplied username exists in the system. When a non-existent email is provided in the login parameter, the endpoint returns an HTTP 400 response (Bad Request). When a valid email is supplied, the endpoint responds with HTTP 200. This difference in server responses creates an observable discrepancy that allows an attacker to reliably determine which emails are registered in the application. By automating requests with a list of possible email addresses, an attacker can quickly build a list of valid accounts without any authentication. The endpoint should return a consistent response regardless of whether the username exists in order to prevent account enumeration. Version 2.0.13 fixes this issue.

A username enumeration vulnerability exists in multiple WSO2 products when Multi-Attribute Login is enabled. In this configuration, the system returns a distinct "User does not exist" error message to the login form, regardless of the validate_username setting. This behavior allows malicious actors to determine which usernames exist in the system based on observable discrepancies in the application's responses. Exploitation of this vulnerability could aid in brute-force attacks, targeted phishing campaigns, or other social engineering techniques by confirming the validity of user identifiers within the system.

OpenSSH through 8.7 allows remote attackers, who have a suspicion that a certain combination of username and public key is known to an SSH server, to test whether this suspicion is correct. This occurs because a challenge is sent only when that combination could be valid for a login session. NOTE: the vendor does not recognize user enumeration as a vulnerability for this product

IBM Aspera Console 3.3.0 through 3.4.8 could allow an attacker to enumerate usernames due to an observable response discrepancy.

A vulnerability, which was classified as problematic, was found in viafintech Barzahlen Payment Module PHP SDK up to 2.0.0. Affected is the function verify of the file src/Webhook.php. The manipulation leads to observable timing discrepancy. The complexity of an attack is rather high. The exploitability is told to be difficult. Upgrading to version 2.0.1 is able to address this issue. The patch is identified as 3e7d29dc0ca6c054a6d6e211f32dae89078594c1. It is recommended to upgrade the affected component. VDB-217650 is the identifier assigned to this vulnerability.

Medtronic CareLink Network allows an unauthenticated remote attacker to initiate a request for security questions to an API endpoint that could be used to determine a valid user account. This issue affects CareLink Network: before December 4, 2025.

Adenza AxiomSL ControllerView through 10.8.1 is vulnerable to user enumeration. An attacker can identify valid usernames on the platform because a failed login attempt produces a different error message when the username is valid.

IBM Guardium Data Encryption (GDE) 5.0.0.2 behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which could facilitate username enumeration. IBM X-Force ID: 213856.

InHand Networks IR615 Router's Versions 2.3.0.r4724 and 2.3.0.r4870 authentication process response indicates and validates the existence of a username. This may allow an attacker to enumerate different user accounts.

The Page Restriction WordPress (WP) – Protect WP Pages/Post plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 1.3.6 via the WordPress core search feature. This makes it possible for unauthenticated attackers to extract sensitive data from posts that have been restricted to higher-level roles such as administrator.

User enumeration vulnerability in Devklan's Alma Blog that affects versions 2.1.10 and earlier. This vulnerability could allow a remote user to retrieve all valid users registered in the application just by looking at the request response.

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 valid users with incorrect passwords. An unauthenticated attacker can exploit this difference to enumerate valid usernames, with no rate limiting or account lockout to impede the process. This issue has been fixed in version 7.2.0.

Dependency-Track is a Component Analysis platform that allows organizations to identify and reduce risk in the software supply chain. Performing a login request against the /api/v1/user/login endpoint with a username that exist in the system takes significantly longer than performing the same action with a username that is not known by the system. The observable difference in request duration can be leveraged by actors to enumerate valid names of managed users. LDAP and OpenID Connect users are not affected. The issue has been fixed in Dependency-Track 4.12.2.

A CWE-204 "Observable Response Discrepancy" in the login page in Q-Free MaxTime less than or equal to version 2.11.0 allows an unauthenticated remote attacker to enumerate valid usernames via crafted HTTP requests.

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 engineering attacks. Attackers can leverage this information to craft targeted phishing campaigns or other malicious activities aimed at tricking users into divulging sensitive data, potentially damaging the organization's reputation and leading to regulatory non-compliance and financial consequences.

Using iterative requests an attacker was able to learn the size of an opaque response, as well as the contents of a server-supplied Vary header. This vulnerability affects Firefox < 119.

An issue was discovered in eZ Publish Ibexa Kernel before 7.5.15.1. The /user/sessions endpoint can be abused to determine account existence.

The password-reset form in ServiceNow Orlando provides different responses to invalid authentication attempts depending on whether the username exists.

A vulnerability has been identified in Mendix Runtime V10 (All versions < V10.17.0 only if the basic authentication mechanism is used by the application), Mendix Runtime V10.12 (All versions < V10.12.11 only if the basic authentication mechanism is used by the application), Mendix Runtime V10.6 (All versions < V10.6.19 only if the basic authentication mechanism is used by the application), Mendix Runtime V8 (All versions < V8.18.33 only if the basic authentication mechanism is used by the application), Mendix Runtime V9 (All versions < V9.24.31 only if the basic authentication mechanism is used by the application). The authentication mechanism of affected applications contains an observable response discrepancy vulnerability when validating usernames. This could allow unauthenticated remote attackers to distinguish between valid and invalid usernames.

UrBackup Server 2.5.31 allows brute-force enumeration of user accounts because a failure message confirms that a username is not valid.

Pimcore is an open source data & experience management platform. In versions prior to 10.1.3, it is possible to enumerate usernames via the forgot password functionality. This issue is fixed in version 10.1.3. As a workaround, one may apply the available patch manually.

Crypto++ (aka Cryptopp) 8.6.0 and earlier contains a timing leakage in MakePublicKey(). There is a clear correlation between execution time and private key length, which may cause disclosure of the length information of the private key. This might allow attackers to conduct timing attacks. NOTE: this report is disputed by the vendor and multiple third parties. The execution-time differences are intentional. A user may make a choice of a longer key as a tradeoff between strength and performance. In making this choice, the amount of information leaked to an adversary is of infinitesimal value

A vulnerability has been identified in Mendix Forgot Password (Mendix 10 compatible) (All versions < V5.4.0), Mendix Forgot Password (Mendix 7 compatible) (All versions < V3.7.3), Mendix Forgot Password (Mendix 8 compatible) (All versions < V4.1.3), Mendix Forgot Password (Mendix 9 compatible) (All versions < V5.4.0). Applications using the affected module are vulnerable to user enumeration due to distinguishable responses. This could allow an unauthenticated remote attacker to determine if a user is valid or not, enabling a brute force attack with valid users.

Piccolo is an ORM and query builder which supports asyncio. In versions 0.120.0 and prior, the implementation of `BaseUser.login` leaks enough information to a malicious user such that they would be able to successfully generate a list of valid users on the platform. As Piccolo on its own does not also enforce strong passwords, these lists of valid accounts are likely to be used in a password spray attack with the outcome being attempted takeover of user accounts on the platform. The impact of this vulnerability is minor as it requires chaining with other attack vectors in order to gain more then simply a list of valid users on the underlying platform. The likelihood of this vulnerability is possible as it requires minimal skills to pull off, especially given the underlying login functionality for Piccolo based sites is open source. This issue has been patched in version 0.121.0.

Proxmox VE prior to 3.2: 'AccessControl.pm' User Enumeration Vulnerability

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.54 and 9.6.0-alpha.43, an attacker can subscribe to LiveQuery with a watch parameter targeting a protected field. Although the protected field value is properly stripped from event payloads, the presence or absence of update events reveals whether the protected field changed, creating a binary oracle. For boolean protected fields, the timing of change events is equivalent to knowing the field value. This issue has been patched in versions 8.6.54 and 9.6.0-alpha.43.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, unauthenticated users can determine whether a specific user is a member of a private group by observing changes in directory results when using the `exclude_groups` parameter. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, disable public access to the user directory via Admin → Settings → hide user profiles from public.

Meow hash 0.5/calico does not sufficiently thwart key recovery by an attacker who can query whether there's a collision in the bottom bits of the hashes of two messages, as demonstrated by an attack against a long-running web service that allows the attacker to infer collisions by measuring timing differences.

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 attacker to enumerate valid usernames and determine whether accounts are active, inactive, or banned — at scale and without solving any captcha — by observing three distinct JSON error responses. Commit e42f54123b460fd1b2ee01f2ce3d4a386e88d157 contains a patch.

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__CUSTOMER_AUTH_BAD_CREDENTIALS) or is unknown (CHECKOUT__CUSTOMER_NOT_FOUND). The "not found" response also echoes the probed email address. This allows an unauthenticated attacker to enumerate valid customer accounts. The storefront login controller correctly unifies both error paths, but the Store API does not — indicating an inconsistent defense. This vulnerability is fixed in 6.7.8.1 and 6.6.10.15.

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 email address belongs to an existing user, is already verified, or does not exist. An attacker can send requests with different email addresses and observe the error codes to determine which email addresses are registered in the application. This is a user enumeration vulnerability that affects any Parse Server deployment with email verification enabled (verifyUserEmails: true). This vulnerability is fixed in 8.6.34 and 9.6.0-alpha.8.

Username enumeration is possible through Bypassing CAPTCHA in On-premise SureMDM Solution on Windows deployment allows attacker to enumerate local user information via error message. This issue affects SureMDM On-premise: 6.31 and below version

Under certain circumstances a CCURE Portal user could enumerate user accounts in CCURE 9000 version 2.90 and prior versions.

Variable response times in the AWS Sign-in IAM user login flow allowed for the use of brute force enumeration techniques to identify valid IAM usernames in an arbitrary AWS account.

The commit 3730880 (April 2023) and v.0.9-beta1 of gugoan Economizzer has a user enumeration vulnerability in the login and forgot password functionalities. The app reacts differently when a user or email address is valid, and when it's not. This may allow an attacker to determine whether a user or email address is valid, or brute force valid usernames and email addresses.

IBM CICS TX Advanced 10.1 could disclose sensitive information to a remote attacker due to observable discrepancy in HTTP responses. IBM X-Force ID: 260814.