CVE-2026-12495

Deferred Deferred - Pending Action

Mercusys MB115-4G Web Interface Stack Buffer Overflow DoS

Publication date: 2026-07-27

Last updated on: 2026-10-24

Assigner: Spanish National Cybersecurity Institute, S.A. (INCIBE)

Description

Denial-of-service (DoS) vulnerability due to a stack buffer overflow in the http_gdpr_decrypt function of the Mercusys MB115-4G device's web interface. An unauthenticated attacker could exploit this vulnerability by sending a specially crafted request to the /cgi/login endpoint, causing memory corruption and the httpd process to crash, resulting in a denial of service for the web administration service.

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Meta Information

Published

2026-07-27

Last Modified

2026-10-24

Generated

2026-11-08

AI Q&A

2026-07-27

EPSS Evaluated

2026-11-07

NVD

CVE-2026-12495

EUVD

EUVD-2026-49144

Affected Vendors & Products

Vendor	Product	Version / Range
mercusys	mb115-4g	From 1.7.0 (inc) to 1.9.0 (inc)
mercusys	mb115-4g	1.9.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-121	A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

Attack-Flow Graph

Executive Summary

CVE-2026-12495 is a stack-based buffer overflow vulnerability in the Mercusys MB115-4G router's web interface. It affects the http_gdpr_decrypt function and allows unauthenticated attackers to send a specially crafted request to the /cgi/login endpoint. This causes memory corruption, crashing the httpd process and resulting in a denial-of-service for the web administration service.

Detection Guidance

To detect this vulnerability, check if your Mercusys MB115-4G device is running firmware versions between 1.7.0 and MB115-4G(EU)_V1_1.9.0. Use the web interface or SSH to verify the firmware version. If the version is within this range, the device is vulnerable.

Impact Analysis

This vulnerability could allow an attacker to disrupt the router's web administration service, making it inaccessible. This could prevent users from managing their router settings, potentially leading to loss of network connectivity or control over the device.

Compliance Impact

This vulnerability does not directly impact compliance with GDPR or HIPAA as it is a technical flaw causing a denial-of-service condition in the device's web interface. However, if the affected device is used in environments subject to these regulations, the disruption of the web administration service could indirectly affect data processing operations or system availability, potentially leading to compliance issues if critical services are impacted.

Mitigation Strategies

Immediately update the device firmware to version V1_1.9.0 or later. If an update is not available, consider isolating the device from untrusted networks or disabling remote administration until patched.

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