CVE-2026-89020

Description

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.

CVSS breakdown

Affected products

• MikroTik / RouterOS0 – 7.23.4
• MikroTik / RouterOS7.24.0 – 7.24.2

References

• MISChttps://forum.mikrotik.com/t/7-24-2-stable-is-released/272800
• MISChttps://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801
• VENDOR_ADVISORYhttps://www.vulncheck.com/advisories/mikrotik-routeros-stack-buffer-overflow-via-tftp-url-path