CVE-2020-20486Public exploitNetwork attack vector

Remote service crash via unchecked ASDU bounds

Published Aug 31, 2021 · Updated Aug 4, 2024

Stack-buffer over-read in IEC104 1.0 allows remote attackers to crash the server via a crafted IEC 60870-5-104 message. In Iec104_Deal_I at IEC10x/Iec104.c:1175, the code dereferences asdu->_addr without first ensuring that the received ASDU remains inside the stack-resident Iec104_RecvBuf. No authentication or user interaction is required; the demonstrated result is an AddressSanitizer abort and process exit, not code execution.

CVSS severity7.5
High
EPSS probability1.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-buffer over-read in IEC104 1.0 allows remote attackers to crash the server via a crafted IEC 60870-5-104 message. In Iec104_Deal_I at IEC10x/Iec104.c:1175, the code dereferences asdu->_addr without first ensuring that the received ASDU remains inside the stack-resident Iec104_RecvBuf. No authentication or user interaction is required; the demonstrated result is an AddressSanitizer abort and process exit, not code execution.

The record

CVE
CVE-2020-20486
Published
Aug 31, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 31, 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 privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

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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