CVE-2021-27221

Name: CVE-2021-27221
Creator: NVD / NIST
Published: 2021-03-19T03:15:12.363+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.1/10EPSS 4.49%

Last modified Jun 17, 2026

CVE-2021-27221 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. MikroTik RouterOS 6.47.9 allows remote authenticated ftp users to create or overwrite arbitrary .rsc files via the /export command. NOTE: the vendor's position is that this is intended behavior because of how user policies work. EPSS estimates a 4.49% chance of exploitation in the next 30 days.

Description

MikroTik RouterOS 6.47.9 allows remote authenticated ftp users to create or overwrite arbitrary .rsc files via the /export command. NOTE: the vendor's position is that this is intended behavior because of how user policies work

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

EPSS Probability

4.49%

90.3th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Mikrotik	Routeros	6.47.9

References

https://onovy.medium.com/routeros-user-with-just-ftp-policy-can-write-to-filesystem-cve-2021-27221-e3e45d780dfeExploit, Third Party Advisory
https://onovy.medium.com/routeros-user-with-just-ftp-policy-can-write-to-filesystem-cve-2021-27221-e3e45d780dfeExploit, Third Party Advisory

Timeline

Published: Mar 19, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-27221?

How severe is CVE-2021-27221?

CVE-2021-27221 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 4.49% probability of exploitation in the next 30 days.

How do I fix CVE-2021-27221?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-27221?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST