CVE-2020-20221Network attack vector

Authenticated service interruption via cerm CPU exhaustion

Published Jul 21, 2021 · Updated Aug 4, 2024

Uncontrolled resource consumption in MikroTik RouterOS before 6.44.6 allows remote authenticated users to interrupt service via a crafted packet. The /nova/bin/cerm process performs unbounded CPU work while handling the packet, driving the system to sustained high load. A valid RouterOS account is required; exploitation slows the device or makes it unresponsive, with no reported confidentiality or integrity impact.

CVSS severity6.5
Medium
EPSS probability2.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in MikroTik RouterOS before 6.44.6 allows remote authenticated users to interrupt service via a crafted packet. The /nova/bin/cerm process performs unbounded CPU work while handling the packet, driving the system to sustained high load. A valid RouterOS account is required; exploitation slows the device or makes it unresponsive, with no reported confidentiality or integrity impact.

The record

CVE
CVE-2020-20221
Published
Jul 21, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 21, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.8NVDAV:N/AC:L/Au:S/C:N/I:N/A:C
6.5NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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