CVE-2026-53904
HighCVSS 7.1Exploitation Probability (EPSS)
Low risk14th percentile - higher than 14% of all known CVEs
Summary
A vulnerability in MCO allows an attacker to lock a victim's account by repeatedly resetting the password. Each reset request invalidates the previous password and temporary passwords, with no limit on the number of resets. An attacker who knows the victim's email and security question answer can effectively deny access to the account.
Risk Assessment
The risk is the potential for permanent account lockout, leading to service disruption and loss of productivity. The requirement to know the security question answer and the limited number of attempts to guess it mitigate the risk to some extent.
Recommendation
Immediately update MCO to the latest patched version if available. If no patch exists, temporarily disable the password reset functionality or implement rate limiting on reset requests per account.
Other vulnerabilities in MCO
See all- CVE-2026-53909Medium
The vulnerability in MCO is due to missing server-side validation of uploaded file types. Validation relies solely on client-side checks, which can be bypassed. An authenticated, low-privileged attacker can upload files of arbitrary types to the server.
- CVE-2026-53908Medium
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, allowing an attacker to enumerate valid usernames and email addresses.
- CVE-2026-53907Medium
Stored Cross‑Site Scripting (XSS) vulnerability in MCO allows an attacker to upload a malicious SVG file as the application logo. The JavaScript code executes when the logo is rendered or opened.
- CVE-2026-53906High
MCO is vulnerable to Path Disclosure and Path Traversal in file handling functionality related to data export and upload. Improper validation of the filename parameter allows writing files to arbitrary locations as well as indirect disclosure of absolute server paths through error messages.
- CVE-2026-53905High
A vulnerability in MCO allows an authenticated low-privileged user to retrieve administrator access control structures via the /customer/servlet/mco/webapi/admin-view-hierarchy/get-acl-tree-structure endpoint due to missing authorization checks. This may expose sensitive permission mappings and internal configuration details.
- CVE-2026-53903High
An IDOR vulnerability in the /customer/servlet/mco/webapi/trading-document/fetchPdfStatement endpoint allows unauthorized access to other users' trading documents. The lack of permission validation enables document retrieval based on a guessable identifier.
- CVE-2026-53902Medium
A vulnerability in MCO allows an authenticated user to modify group membership without proper authorization checks, leading to privilege escalation. An attacker can add themselves to arbitrary groups by providing a valid group ID, which can be obtained from other application functionalities or guessed via brute-force.
Original NVD description (English source)
MCO is vulnerable to Account Denial of Service due to improper implementation of password reset functionality. Each password reset request invalidates previously set password as well as previously issued temporary passwords, furthermore, password resets are not limited in any way. An attacker who provides victim's email and answer to their security question, can successfully initiate the reset process and continuously invalidate credentials, effectively locking the victim out of their account. Answering security questions has a limited number of tries which lowers the risk of this vulnerability. Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 25.3.3.1 but may also affect other versions.