MikroTik RouterOS pre-auth RCE flaw patched
An unauthenticated integer underflow in MikroTik RouterOS's web management service can lead to root RCE or DoS via a single crafted HTTP request; patch to 7.24+.
Sourcecisa.gov — open the original
What to check
- Applies to
- The 1 CVE named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- No exploitation in the wild and no public exploit is recorded for the CVEs named.
CISA has published an advisory for MikroTik RouterOS versions prior to 7.24, detailing CVE-2026-84411, an integer underflow (CWE-191) in the HTTP request body handling of the web management service. The flaw is reachable pre-authentication, meaning an unauthenticated network attacker can send a single crafted HTTP request to achieve arbitrary code execution as root, or alternatively cause a denial of service.
MikroTik RouterOS is widely deployed worldwide across communications and IT infrastructure, making this a broadly relevant issue for organizations using MikroTik routers for network management. MikroTik (headquartered in Latvia) recommends upgrading to RouterOS 7.23 or later via the official download page. CISA notes no known public exploitation has been reported at this time, but given the pre-auth, single-request nature of the exploit, prompt patching is advised.
Defenders should ensure RouterOS web management interfaces are not exposed to the internet, place management access behind firewalls/VPNs, and prioritize upgrading affected devices to the fixed version. This advisory follows standard CISA ICS guidance on network segmentation and minimizing exposure of control system and network infrastructure devices.
Mentioned in this report
Source reporting: https://www.cisa.gov/news-events/ics-advisories/icsa-26-272-06
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