Overview
CVE-2025-50399 identifies a buffer overflow vulnerability found in the FAST FAC1200R F400_FAC1200R_Q router firmware. This vulnerability allows attackers to potentially execute arbitrary code or cause a denial-of-service condition by exploiting a flaw in the handling of the password parameter. A successful exploit can compromise the router’s security, potentially granting unauthorized access to the network or disrupting its operation.
Technical Details
The vulnerability resides within the sub_80435780 function of the FAST FAC1200R firmware. Specifically, the code fails to properly validate the length of the password parameter before copying it into a fixed-size buffer. By providing a password exceeding the buffer’s capacity, an attacker can overwrite adjacent memory regions, potentially leading to code execution or system instability. Detailed analysis and proof-of-concept exploits have been published, highlighting the ease with which this vulnerability can be triggered.
CVSS Analysis
Currently, the CVSS score and severity for CVE-2025-50399 are listed as N/A. This may be due to the vulnerability being recently disclosed or awaiting a comprehensive risk assessment. However, buffer overflow vulnerabilities typically warrant a high CVSS score, considering the potential for remote code execution and complete system compromise. A more thorough risk assessment is needed to determine the precise CVSS score. Based on similar vulnerabilities a CVSS score of 7.0 or higher can be expected.
Possible Impact
The successful exploitation of CVE-2025-50399 can have severe consequences:
- Remote Code Execution (RCE): An attacker could execute arbitrary code on the router, potentially gaining complete control over the device.
- Denial-of-Service (DoS): The vulnerability could be exploited to crash the router, disrupting network connectivity.
- Data Theft: An attacker with control over the router could intercept and steal sensitive data transmitted over the network.
- Malware Propagation: The compromised router could be used as a launching point for malware attacks against other devices on the network or on the Internet.
- Botnet Recruitment: The compromised router could be added to a botnet, allowing attackers to launch distributed attacks.
Mitigation and Patch Steps
Currently, there are no official patches available from FAST to address this vulnerability. Users of FAST FAC1200R F400_FAC1200R_Q routers are advised to take the following mitigation steps:
- Disable Remote Administration: If possible, disable remote administration access to the router to reduce the attack surface.
- Use Strong Passwords: While this vulnerability bypasses standard password authentication, using a strong and unique password for other router settings can help mitigate other potential attacks.
- Monitor Network Traffic: Monitor network traffic for suspicious activity, such as unauthorized access attempts or unusual data transfers.
- Firewall Protection: Ensure that your firewall is properly configured to block unauthorized access to the router.
- Contact the Vendor: Contact FAST support and urge them to release a security patch for this vulnerability.
- Consider Alternative Routers: If a patch is not forthcoming and the risk is unacceptable, consider replacing the vulnerable router with a more secure alternative.
We will update this article with patch information as soon as it becomes available.
