CVE-2026-51926

Deferred Deferred - Pending Action

Authentication Bypass in FSM Client via User Enumeration

Publication date: 2026-07-09

Last updated on: 2026-07-10

Assigner: MITRE

Description

An issue in docuForm GmbH FSM Client v.11.11c allows a remote attacker to obtain sensitive information via the login.php component. A vulnerability was identified in the authentication mechanism that allows user enumeration through the login interface. An attacker can differentiate between valid and invalid usernames based on variations in server responses. This information can be leveraged to identify existing accounts and facilitate further attacks, including brute-force or credential stuffing.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-07-09

Last Modified

2026-07-10

Generated

2026-07-11

AI Q&A

2026-07-10

EPSS Evaluated

N/A

NVD

CVE-2026-51926

Affected Vendors & Products

Vendor	Product	Version / Range
docuform_gmbh	fsm_client	11.11c

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-203	The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes security-relevant information about the state of the product, such as whether a particular operation was successful or not.

Attack-Flow Graph

Detection Guidance

This vulnerability can be detected by testing the login.php component for user enumeration. An attacker can send login requests with different usernames and observe variations in server responses to determine valid usernames.

Specific commands or tools to detect this vulnerability are not provided in the available information.

Mitigation Strategies

Immediate mitigation steps are not detailed in the provided information.

Generally, to mitigate user enumeration vulnerabilities, it is recommended to standardize server responses for both valid and invalid login attempts to avoid revealing information about username validity.

Executive Summary

This vulnerability exists in docuForm GmbH FSM Client version 11.11c, specifically in the login.php component. It allows a remote attacker to perform user enumeration by exploiting differences in server responses during the authentication process. Essentially, the attacker can tell whether a username is valid or invalid based on how the server responds, which reveals sensitive information about existing user accounts.

Impact Analysis

The vulnerability can impact you by enabling attackers to identify valid usernames on your system. With this information, attackers can launch further attacks such as brute-force attempts or credential stuffing to gain unauthorized access to accounts. This increases the risk of account compromise and potential data breaches.

Compliance Impact

This vulnerability allows remote attackers to perform user enumeration via the login interface by distinguishing valid usernames from invalid ones based on server response differences.

Such user enumeration can lead to the exposure of sensitive information about user accounts, which may increase the risk of further attacks like brute-force or credential stuffing.

While the CVE description does not explicitly mention compliance impacts, the exposure of sensitive user information and potential unauthorized access attempts could negatively affect compliance with data protection regulations such as GDPR and HIPAA, which require safeguarding personal and sensitive data against unauthorized disclosure.

Hi! I’m here to help you understand CVE-2026-51926. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70