How severe is CVE-2021-27221?

CVE-2021-27221 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2021-27221 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (90th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27221?

CVE-2021-27221 affects Mikrotik Routeros. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27221?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-27221 published?

CVE-2021-27221 was published on 2021-03-19 and last updated on 2026-06-17.

CVE-2021-27221

CVE-2021-27221 is a high-severity vulnerability in Mikrotik Routeros with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 8.5
EPSS exploit prediction: 4% (90th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Mikrotik Routeros
Published: 2021-03-19
Last modified: 2026-06-17

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

Frequently asked questions

What is CVE-2021-27221?: 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
How severe is CVE-2021-27221?: CVE-2021-27221 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2021-27221 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (90th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27221?: CVE-2021-27221 affects Mikrotik Routeros. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27221?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-27221 published?: CVE-2021-27221 was published on 2021-03-19 and last updated on 2026-06-17.

References

https://onovy.medium.com/routeros-user-with-just-ftp-policy-can-write-to-filesystem-cve-2021-27221-e3e45d780dfe

Affected products (1)

cpe:2.3:o:mikrotik:routeros:6.47.9:*:*:*:-:*:*:*

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CVE-2018-14847 — Critical (CVSS 9.1): MikroTik RouterOS through 6.42 allows unauthenticated remote attackers to read arbitrary files and remote authenticated…
CVE-2022-45313 — High (CVSS 8.8): Mikrotik RouterOs before stable v7.5 was discovered to contain an out-of-bounds read in the hotspot process. This…

All CVEs affecting Mikrotik Routeros →

Threat intelligence

Threat-intel indicators referencing this CVE:

185.193.240.246 (ipv4-addr)