CVE-2026-89020

What it is

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. On older RouterOS versions, this overflow is not limited to crashing the process: the deterministic overwrite of saved registers is exploitable to achieve persistent privilege escalation on the device. On versions with intact exploit mitigations, the impact is limited to a crash of the mtget worker process.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.6% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2026-09-10 16:23 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-09-14 19:17 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-11-06 20:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.6% in the next 30 days (EPSS).
• Severity: 8.7 HIGH (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2026-09-14 19:17 UTC

Last modified

2026-11-06 20:17 UTC

Exploit probability

0.6% · EPSS, next 30 days

Weakness

CWE-121

Record status

Awaiting Analysis

Attack profile CVSS 4.0 · 8.7

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

Low

User interaction

None

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-89020.md and follow it. Check whether this project is affected by CVE-2026-89020. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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