CVE-2026-84411 MikroTik RouterOS Integer Underflow
Unauthenticated attackers can achieve root code execution or cause denial of service via integer underflow in RouterOS web management.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-84411?
CVE-2026-84411 is a critical vulnerability in MikroTik RouterOS, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-191
Which versions are affected by CVE-2026-84411?
How do I fix CVE-2026-84411?
No fix has been published for CVE-2026-84411 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-84411 being exploited?
There is no known exploitation of CVE-2026-84411 in the wild and no public exploit code.
Public exploit code: 2 proofs of concept on GitHub.
Sources
Also known as GHSA-xj4h-hf2x-2q43.