CVE-2017-20149: The Mikrotik RouterOS web server allows memory corruption in releases before Stable 6.38.5 and Long-term 6.37.5, aka…

Is it exploited?

Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of 29 Oct 2026.

VulnCheck KEV lists it since 28 Mar 2018. It cites 3 public reports, the first from 28 Mar 2018.

• blog.netlab.360.com
• ndss-symposium.org
• cve.org

How likely is exploitation in the next 30 days?

2.5%

EPSS score, percentile 84.5 of all scored records. A probability estimated by FIRST, not a report of exploitation.

CISA's SSVC assessment in the CVE record lists exploitation as poc.

How severe?

9.8 Critical

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Not stated. The CVE record gives vendor and product as “n/a” and the version as “unspecified”.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; VulnCheck KEV, as of 30 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 30 Oct 2026. About the data.

Description

The Mikrotik RouterOS web server allows memory corruption in releases before Stable 6.38.5 and Long-term 6.37.5, aka Chimay-Red. A remote and unauthenticated user can trigger the vulnerability by sending a crafted HTTP request. An attacker can use this vulnerability to execute arbitrary code on the affected system, as exploited in the wild in mid-2017 and later.

Source: CVE List, as of 30 Oct 2026. About the data.

What to do

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

This summary is based on the CVE record as of 30 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

The CVE record does not name affected products or versions: vendor and product are “n/a” and the version is “unspecified”.

Source: CVE List, as of 30 Oct 2026. About the data.

Timeline