CVE-2026-84411

Received Received - Intake

Integer Underflow in MikroTik RouterOS Web Management Service

Publication date: 2026-10-02

Last updated on: 2026-10-02

Assigner: ICS-CERT

Description

The web management service in affected RouterOS versions contains an integer underflow in its HTTP request body handling that is reachable before authentication. This can be leveraged by an unauthenticated network attacker to achieve arbitrary code execution as root, or to cause a denial of service, using a single crafted request.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-10-02

Last Modified

2026-10-02

Generated

2026-10-03

AI Q&A

2026-10-03

EPSS Evaluated

N/A

NVD

CVE-2026-84411

EUVD

EUVD-2026-91836

Affected Vendors & Products

Vendor	Product	Version / Range
mikrotik	routeros	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-191	The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

Attack-Flow Graph

Executive Summary

This vulnerability is an integer underflow in the HTTP request body handling of the web management service in certain RouterOS versions. It is accessible without authentication and can be exploited by a network attacker to execute arbitrary code as root or cause a denial of service with a single crafted request.

Detection Guidance

This vulnerability involves an integer underflow in RouterOS web management service. Detection requires checking RouterOS versions for affected releases and inspecting network traffic for malformed HTTP requests targeting the web interface. No specific commands are provided in the context.

Impact Analysis

An unauthenticated attacker could gain full control of the affected device, execute arbitrary code as root, or crash the system causing a denial of service. This could lead to network compromise, data breaches, or service disruption.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Organizations may face compliance violations, legal penalties, and reputational damage if exploited.

Mitigation Strategies

Immediately update RouterOS to the latest patched version to address the integer underflow vulnerability. Disable remote management access if not required and restrict HTTP/HTTPS access to trusted IP addresses only. Monitor network traffic for unusual requests targeting the web management service.

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