CVE-2025-50401

CriticalPublic PoC

Published: 16 December 2025

Published

16 December 2025

Modified

22 December 2025

KEV Added

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Patch

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CVSS Score 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Score 0.0011 29.6th percentile

Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-50401 is a critical-severity Classic Buffer Overflow (CWE-120) vulnerability in Mercurycom D196G Firmware. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 29.6th 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 are NIST 800-53 SI-10 (Information Input Validation) and SI-16 (Memory Protection).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190). What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Directly remediates the buffer overflow vulnerability in the router firmware by requiring timely patching or replacement of the affected Mercury D196G version.

SI-10 Information Input Validation good match

prevent

Prevents exploitation by enforcing strict validation of the password parameter to avoid buffer overflow in sub_404CAEDC.

SI-16 Memory Protection good match

prevent

Mitigates buffer overflow impacts through memory protections like ASLR and DEP, hindering remote code execution even if input validation fails.

MITRE ATT&CK Enterprise TechniquesAI

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 →

Why these techniques?

Buffer overflow in router firmware allows remote unauthenticated exploitation of a public-facing application/service, enabling RCE.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

Mercury D196G d196gv1-cn-up_2020-01-09_11.21.44 is vulnerable to Buffer Overflow in the function sub_404CAEDC via the parameter password.

Deeper analysisAI

CVE-2025-50401 is a buffer overflow vulnerability (CWE-120) in the Mercury D196G router firmware version d196gv1-cn-up_2020-01-09_11.21.44. The flaw occurs in the function sub_404CAEDC when processing the password parameter. Published on 2025-12-16, it carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), marking it as critical due to its potential for severe impact.

A remote, unauthenticated attacker can exploit this vulnerability over the network with low complexity and no user interaction required. Exploitation enables high-impact compromise, including unauthorized access to confidential data, modification of system integrity, and disruption of availability, likely leading to remote code execution on the affected device.

Proof-of-concept details are available in the GitHub repository at https://github.com/sezangel/IOT-vul/tree/main/Mercury/D196G/1. No vendor advisories or patches are referenced in the CVE information.