CVE-2021-21778Network attack vector

Communication loss via uncaught ASDU parsing exception

Published Aug 25, 2021 · Updated Aug 3, 2024

Reachable assertion in lib60870.NET 2.2.0 allows remote attackers to halt application communications via a malformed IEC104 message. The ASDU constructor in lib60870/CS101/ASDU.cs throws ASDUParsingException when an information-transfer message is shorter than the computed ASDU header, and the exception escapes the caller. An unauthenticated network peer can terminate the hosting client or server process, stopping communications until the application restarts.

CVSS severity7.5
High
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Reachable assertion in lib60870.NET 2.2.0 allows remote attackers to halt application communications via a malformed IEC104 message. The ASDU constructor in lib60870/CS101/ASDU.cs throws ASDUParsingException when an information-transfer message is shorter than the computed ASDU header, and the exception escapes the caller. An unauthenticated network peer can terminate the hosting client or server process, stopping communications until the application restarts.

The record

CVE
CVE-2021-21778
Published
Aug 25, 2021
Updated
Aug 3, 2024
Vendor
MZ Automation GmbH
Product
lib60870.NET
Classifications
CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=MZ Automation GmbH lib60870.NET 2.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MZ Automation GmbH · lib60870.NETversion=MZ Automation GmbH lib60870.NET 2.2.0

Published CVSS scores

7.5Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-617Reachable Assertion
T1499.004Application or System Exploitation

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo