CVE-2018-25226 Overview
CVE-2018-25226 is a buffer overflow vulnerability in FTPShell Server 6.83 that triggers a denial of service when a local attacker submits an overlong string to the account name field. The flaw resides in the Manage FTP Accounts interface, specifically in the Account name to ban parameter. Pasting a 417-byte payload into that field crashes the application. The issue is tracked under CWE-787 (Out-of-bounds Write) and affects the FTP server component used to host and administer FTP services on Windows hosts.
Critical Impact
A local user with access to the FTPShell Server administration UI can crash the service by submitting a 417-byte string in the account ban field, disrupting FTP availability for all connected clients.
Affected Products
- FTPShell Server 6.83
- ftpshell:ftpshell_server (CPE: cpe:2.3:a:ftpshell:ftpshell_server:6.83:*:*:*:*:*:*:*)
- Windows installations exposing the Manage FTP Accounts interface
Discovery Timeline
- 2026-03-30 - CVE-2018-25226 published to NVD
- 2026-03-31 - Last updated in NVD database
Technical Details for CVE-2018-25226
Vulnerability Analysis
FTPShell Server 6.83 fails to bound-check input written to a fixed-size buffer in the account management workflow. When an administrator or local user pastes a 417-byte string into the Account name to ban field within the Manage FTP Accounts dialog, the application writes past the buffer boundary and terminates. The crash interrupts active FTP sessions and removes the service until an operator restarts it.
The defect maps to CWE-787, Out-of-bounds Write. The condition is reachable only by a user with access to the local administration interface, which limits the population of viable attackers but does not eliminate impact in multi-user or shared administrative environments. Public proof-of-concept material is available through Exploit-DB #46430 and the VulnCheck Advisory - FTPShell DoS.
Root Cause
The root cause is missing input length validation on the account name field before the value is copied into a stack or heap buffer. The application accepts arbitrary-length input from the GUI without truncation or rejection, producing an out-of-bounds write at the 417-byte boundary.
Attack Vector
Exploitation requires local access to the FTPShell Server administration UI. An attacker opens Manage FTP Accounts, pastes a 417-byte payload into the Account name to ban field, and submits the form. The server process crashes immediately, denying FTP service. The vulnerability does not provide code execution evidence in the public advisories and is classified as denial of service.
No verified exploit code is reproduced here. Refer to Exploit-DB #46430 for the published proof-of-concept payload format.
Detection Methods for CVE-2018-25226
Indicators of Compromise
- Unexpected termination of the FTPShell Server process on a host running version 6.83.
- Windows Application event log entries showing an access violation in the FTPShell Server executable.
- Repeated FTP service outages correlated with administrative logons to the Manage FTP Accounts interface.
Detection Strategies
- Monitor process crash and Windows Error Reporting events for the FTPShell Server binary on affected hosts.
- Alert on abnormally long values written to FTPShell configuration files or account databases.
- Correlate local interactive logons on FTP servers with subsequent service stop events.
Monitoring Recommendations
- Track FTP service availability with active health checks and alert on unscheduled downtime.
- Forward Windows Application and Security event logs from FTPShell hosts to a centralized log platform for retention and search.
- Review administrative access to the FTPShell management console and restrict it to named operators.
How to Mitigate CVE-2018-25226
Immediate Actions Required
- Restrict local and remote desktop access to the FTPShell Server host to trusted administrators only.
- Audit the list of accounts authorized to open the Manage FTP Accounts interface and remove unneeded users.
- Configure automatic service restart on failure to limit downtime if the process crashes.
Patch Information
No vendor patch is referenced in the NVD entry for CVE-2018-25226. Operators should consult the FTPShell Download Server page for newer releases and verify whether a fixed version is available before deployment. If a fixed build is not available, treat the application as end-of-support and plan migration to a maintained FTP server.
Workarounds
- Replace FTPShell Server 6.83 with a maintained FTP/SFTP server that receives security updates.
- Block network and console access to the administration interface using host firewall rules and OS-level access controls.
- Enforce input length limits at the operator procedure level and avoid pasting untrusted strings into the account management fields.
- Run the FTPShell service under a least-privilege account and isolate it on a dedicated host to limit blast radius.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
