CVE-2026-89020 is a vulnerability in MikroTik Routeros
Published on September 14, 2026
MikroTik RouterOS Stack Buffer Overflow via TFTP URL Path
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.
Vulnerability Analysis
CVE-2026-89020 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
What is a Stack Overflow Vulnerability?
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
CVE-2026-89020 has been classified to as a Stack Overflow vulnerability or weakness.
Products Associated with CVE-2026-89020
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Affected Versions
MikroTik RouterOS:- Before 7.23.4 is affected.
- Version 7.24.0 and below 7.24.2 is affected.