CVE-2021-27221 json
MikroTik RouterOS 6.47.9 allows remote authenticated ftp users to create or overwrite arbitrary .rsc files via the /export command.
published 2021-03-19 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-13986
- cvss
- 8.1
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 4.0%
- EPSS 4.0% chance of exploitation in 30 days, percentile 90%
- public exploits
- 0
- none known
Summary
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
Exploit prediction
4.04% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- onovy.medium.com https://onovy.medium.com/routeros-user-with-just-ftp-policy-can-write-to-filesystem-cve-2021-27221-e3e45d780dfe referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 8.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H |
| NVD | 2.0 | 8.5 | AV:N/AC:L/Au:S/C:N/I:C/A:C |
References
-
onovy.medium.com
/routeros-user-with-just-ftp-policy-can-write-to-filesystem-cve-2021-27221-e3e45d780dfe
exploit, third-party-advisory
Sources
- CVE List CVE-2021-27221
- NVD CVE-2021-27221
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.