What is CVE-2020-20254?

CVE-2020-20254 is a medium-severity vulnerability in Mikrotik Routeros, classified under Out-of-bounds Write. CVSS score: 6.5/10. Published 2021-05-18.

How severe is CVE-2020-20254?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Buffer overflow in Mikrotik Routeros

CVE-2020-20254

Mikrotik RouterOs before 6.47 (stable tree) suffers from a memory corruption vulnerability in the /nova/bin/lcdstat process. An authenticated remote attacker can cause a Denial of Service (NULL pointer dereference).

Vulnerability class: Buffer Overflow

Published 2021-05-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.021 (80.9th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 81st percentile — 80.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.021 · newest: 0.021 · change: 0.000

Affected products

Mikrotik Routeros

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

github.com/cq674350529/pocs_slides/blob/master/pocs/MikroTik/vul_lcdstat_2/READ… (Third Party Advisory, Broken Link)
seclists.org/fulldisclosure/2021/May/14 (mailing-list, Exploit, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2020-20254?: CVE-2020-20254 is a medium-severity vulnerability in Mikrotik Routeros, classified under Out-of-bounds Write. CVSS score: 6.5/10. Published 2021-05-18.
How severe is CVE-2020-20254?: Medium severity. CVSS v3 base score is 6.5 out of 10.