Stack-Based Buffer Overflow in MikroTik RouterOS Affecting Authenticated Users
CVE-2026-89020

8.7HIGH

Key Information:

Vendor

Mikrotik

Status
Routeros
Vendor
CVE Published:
14 September 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-89020?

MikroTik RouterOS versions before 7.23.4 (long-term) and 7.24.2 (stable) are susceptible to a stack-based buffer overflow within the mtget binary's TFTP RRQ builder function. This vulnerability allows authenticated users to cause the mtget worker process to crash by supplying a specially crafted URL path of 507 bytes or more through the /tool fetch command. This attack triggers a write outside the designated buffer, leading to process termination without requiring any special privileges beyond read-only access, enabling potential exploitation despite the absence of a reachable TFTP server.

Affected Version(s)

RouterOS 6.0.0 < 6.49.21

RouterOS 7.0.0 < 7.23.4

RouterOS 7.24.0 < 7.24.2

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-89020 - Proof of Concept

References

https://forum.mikrotik.com/t/7-24-2-stable-is-released/27...
patchrelease-notes
https://forum.mikrotik.com/t/7-23-4-long-term-is-released...
release-notespatch
https://www.vulncheck.com/advisories/mikrotik-routeros-st...
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc.
.