Vulnerability · Published Oct 2, 2026 · Assigned by icscert
CVE-2026-84411MikroTik RouterOS Integer Underflow
Critical 9.8
In plain English
A critical-severity security flaw in RouterOS from MikroTik. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 59% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Official 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.
Affected products (as reported)
Weakness: CWE-191 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H