Security Resilience

CVE-2025-50399

Memory Safety in Fastcom Fac1200R Firmware f400_fac1200r_q

Public PoCMemory Safety
Published
26 November 2025
Modified
02 January 2026
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0042 35th percentile
Risk Priority 71 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2025-50399 is a critical-severity Classic Buffer Overflow (CWE-120) vulnerability in Fastcom Fac1200R Firmware. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Server (T1584.004); ranked at the 35th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2025-50399, published on 2025-11-26, is a buffer overflow vulnerability (CWE-120) affecting the FAST FAC1200R F400_FAC1200R_Q firmware or component. The issue resides in the function sub_80435780, which can be triggered via the password parameter. It has a CVSS v3.1 base score of 9.8, indicating critical severity due to its network accessibility, low attack complexity, lack of required privileges or user interaction, and high impacts on confidentiality, integrity, and availability.

An unauthenticated attacker with network access to the affected device can exploit this vulnerability remotely with low complexity and no user interaction. Successful exploitation could allow arbitrary code execution, potentially leading to full system compromise, data exfiltration, modification of device configurations, or denial of service.

References for this vulnerability are hosted on GitHub at https://github.com/sezangel/IOT-vul/tree/main/FAST/FAC1200R/1, which likely contain proof-of-concept details or analysis, though no official vendor advisories or patches are detailed in the available information.

EU & UK References

Vulnerability Data

FAST FAC1200R F400_FAC1200R_Q is vulnerable to Buffer Overflow in the function sub_80435780 via the parameter password.

CWE(s)
CWE-120

Related Threats

MITRE ATT&CK Enterprise Techniques

T1584.004 Server Resource Development
Adversaries may compromise third-party servers that can be used during targeting.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-50402Same product: Fastcom Fac1200R
CVE-2024-41285Same vendor: Fastcom
CVE-2025-25635Shared CWE-120
CVE-2023-30280Shared CWE-120
CVE-2024-34252Shared CWE-120
CVE-2018-25356Shared CWE-120
CVE-2023-22754Shared CWE-120
CVE-2024-0762Shared CWE-120
CVE-2025-46035Shared CWE-120
CVE-2024-29243Shared CWE-120

Affected Assets

fastcom
fac1200r firmware
f400_fac1200r_q

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V5.2.1

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and analysis can find missing size checks before deployment.

SI-10 Information Input Validation good match

Input validation directly enforces size checks before buffer copies.

SA-8 Security and Privacy Engineering Principles partial match

Engineering principles require bounds checking and safe buffer handling in design.

SI-16 Memory Protection partial match

Memory protection limits the impact of an overflow once it occurs.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
blocks

Secure development practices directly enforce bounds checking and input validation that prevent classic buffer overflows.

ID.RA-01 partial match
blocks

Vulnerability identification processes such as code review or scanning detect classic buffer overflows before exploitation.

PR.PS-02 partial match
blocks

Routine patching replaces vulnerable code containing unchecked buffer copies with corrected versions.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance can detect buffer overflows through fuzzing and static analysis, though it does not prevent them at the source.

A.8.28 Secure coding partial match
prevents

Secure coding directly requires bounds-checked memory operations, addressing the root cause of CWE-120.

References