CVE-2025-5220 Overview
CVE-2025-5220 is a buffer overflow vulnerability in FreeFloat FTP Server version 1.0.0. The flaw resides in the GET Command Handler component and can be triggered remotely without authentication. An attacker who sends a crafted GET command can corrupt memory within the FTP service process. Public exploit details have been disclosed, increasing the likelihood of opportunistic attacks against exposed instances. The vulnerability is tracked under [CWE-119] (improper restriction of operations within memory buffer bounds) and [CWE-120] (classic buffer overflow).
Critical Impact
Remote, unauthenticated attackers can trigger memory corruption in the FTP service through a malformed GET command, potentially leading to denial of service or further exploitation.
Affected Products
- FreeFloat FTP Server 1.0.0
- Component: GET Command Handler
- Vendor: FreeFloat
Discovery Timeline
- 2025-05-27 - CVE-2025-5220 published to the National Vulnerability Database (NVD)
- 2025-06-09 - Last updated in NVD database
Technical Details for CVE-2025-5220
Vulnerability Analysis
The vulnerability resides in how FreeFloat FTP Server 1.0.0 processes the GET command. The server fails to enforce length boundaries on attacker-supplied input passed to the GET Command Handler. Excessively long arguments overflow a fixed-size buffer, overwriting adjacent memory in the FTP service process.
The attack requires no authentication and no user interaction. An attacker establishes a TCP session to the FTP service and issues a malformed GET request. Because the issue affects core FTP command parsing, any reachable instance of FreeFloat FTP Server 1.0.0 is exposed. The EPSS score for this CVE is 0.479% (65th percentile).
Root Cause
The root cause is missing bounds checking when copying user-controlled data into a stack or heap buffer inside the GET command parsing routine. Categorized as [CWE-119] and [CWE-120], the defect allows input length to exceed the destination buffer capacity. FreeFloat FTP Server is an abandoned product, and no upstream code-level fix has been issued.
Attack Vector
The attack vector is network-based. An unauthenticated remote attacker connects to the FTP listener (typically TCP/21) and submits an oversized argument to the GET command. The overflow corrupts process memory, which can crash the server (denial of service) or, in some exploitation scenarios, redirect control flow. A public exploit description is hosted at the Fitoxs Exploit Description and indexed at VulDB #310316.
No verified exploit code is reproduced here. Refer to the public references for technical proof-of-concept details.
Detection Methods for CVE-2025-5220
Indicators of Compromise
- Unexpected crashes or restarts of the FreeFloat FTP Server process on hosts running version 1.0.0.
- FTP sessions containing GET commands with abnormally long argument strings (hundreds to thousands of bytes).
- Inbound TCP/21 connections from untrusted sources followed by service termination events.
- Anomalous child process creation or memory access violations originating from the FTP server binary.
Detection Strategies
- Inspect FTP traffic with network IDS signatures that flag GET command arguments exceeding RFC-reasonable lengths.
- Correlate FTP service crash events with preceding inbound connections in endpoint telemetry.
- Audit hosts for the presence of the FreeFloat FTP Server 1.0.0 binary and expose the inventory to vulnerability management tooling.
Monitoring Recommendations
- Log all inbound FTP sessions, including full command arguments, to a centralized SIEM for retrospective analysis.
- Alert on repeated TCP/21 connection attempts followed by service unavailability within a short window.
- Monitor process integrity for the FreeFloat FTP Server executable and trigger alerts on unexpected termination or memory faults.
How to Mitigate CVE-2025-5220
Immediate Actions Required
- Decommission FreeFloat FTP Server 1.0.0 and replace it with a maintained FTP or SFTP solution.
- Restrict inbound access to TCP/21 using host-based and network firewalls, allowing only trusted source addresses.
- Identify all hosts running the affected binary through asset inventory and vulnerability scanning.
- Place any unavoidable instances behind a VPN or jump host to remove direct internet exposure.
Patch Information
FreeFloat FTP Server is not actively maintained, and no vendor patch is available for CVE-2025-5220. Migration to a supported file transfer product is the recommended remediation path. Track the advisory at VulDB Critical Threat ID #310316 for any future updates.
Workarounds
- Block TCP/21 at the perimeter for hosts that do not require external FTP access.
- Enforce strict allow-lists of source IP addresses for any required FTP connectivity.
- Terminate the FreeFloat FTP Server service on systems where its functionality is not actively used.
- Apply network segmentation to isolate legacy FTP hosts from sensitive internal networks.
# Example: block inbound FTP at the host firewall on Windows
netsh advfirewall firewall add rule name="Block-FTP-21" dir=in action=block protocol=TCP localport=21
# Example: block inbound FTP using iptables on Linux
iptables -A INPUT -p tcp --dport 21 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
