CVE-2026-89020: MikroTik RouterOS

Medium severity, CVSS 4.3. EPSS: 0.5% chance of exploitation in the next 30 days.

MikroTik RouterOS before 7.23.4 (long-term) and 7.24.2 (stable) contains a stack-based buffer overflow vulnerability in the mtget binary's TFTP RRQ builder function that allows authenticated users to crash the mtget worker process by supplying a URL path of 507 bytes or more to the /tool fetch command; the first write outside the 528-byte buffer occurs at 505 bytes. Attackers can trigger the overflow by issuing a fetch command with a crafted tftp:// URL path, which causes an unbounded rep movsb instruction to overwrite saved registers at a deterministic offset, crashing the process without requiring a reachable TFTP server or elevated privileges beyond read-only group membership.

Affected products

• MikroTik RouterOS: before 7.23.4 (fixed in 7.23.4); from 7.24.0, before 7.24.2 (fixed in 7.24.2)

Published 2026-09-14. Last modified 2026-09-24.