CVE-2020-13559Network attack vector

Service crash via traffic-logging loop exhaustion

Published Jan 11, 2021 · Updated Aug 4, 2024

Denial of service in FreyrSCADA IEC 60870-5-104 Server Simulator 21.04.028 allows remote attackers to crash it via a crafted packet. The traffic-logging display loop compares a one-byte index with a two-byte packet length, so packets longer than 255 bytes wrap the index and allocate memory indefinitely. Network access to the IEC 104 service is sufficient; memory exhaustion terminates the simulator without disclosing or modifying data.

CVSS severity5.9
Medium
EPSS probability1.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in FreyrSCADA IEC 60870-5-104 Server Simulator 21.04.028 allows remote attackers to crash it via a crafted packet. The traffic-logging display loop compares a one-byte index with a two-byte packet length, so packets longer than 255 bytes wrap the index and allocate memory indefinitely. Network access to the IEC 104 service is sufficient; memory exhaustion terminates the simulator without disclosing or modifying data.

The record

CVE
CVE-2020-13559
Published
Jan 11, 2021
Updated
Aug 4, 2024
Vendor
FreyrSCADA Embedded Solution
Product
IEC 60870-5-104 Server Simulator
Classifications
CWE-1024, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 11, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=IEC-60879-5-104 Server Simulator 21.04.028

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreyrSCADA Embedded Solution · IEC 60870-5-104 Server Simulatorversion=IEC-60879-5-104 Server Simulator 21.04.028

Published CVSS scores

5.9Cisco TalosCVSS:3.0/AV:N/AC:H/PR:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1024Comparison of Incompatible Types
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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