CVE-2026-84411 PUBLISHED

MikroTik RouterOS Integer Underflow

Assigner: icscert
Reserved: 01.09.2026 Published: 02.10.2026 Updated: 02.10.2026

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

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	High
Privileges Required	None	Integrity Impact	High
User Interaction	None	Availability Impact	High

CVSS 3.1

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS Score: 9.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	MikroTik
Product	RouterOS
Versions	Default: unaffected affected from 0 to 7.24 (excl.) Version 7.24 is unaffected

Solutions

MikroTik recommends users update RouterOS to version 7.24 or later. The upgrade can be downloaded from the MikroTik website. https://mikrotik.com/download

References

Problem Types

CWE-191 CWE