CVE-2020-28393Network attack vector

Permanent service interruption via malformed OSPF LSA fields

Published May 12, 2021 · Updated Aug 4, 2024

Incorrect calculation in Siemens SCALANCE XM-400 and XR-500 before 6.4 allows remote attackers to cause a permanent service interruption. The OSPF implementation incorrectly handles the number of LSA fields when other packet fields are modified, leaving the device in a persistent denial-of-service state. OSPF must be enabled, and receipt of a crafted OSPF packet can permanently interrupt network switching operations.

CVSS severity7.5
High
EPSS probability1.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect calculation in Siemens SCALANCE XM-400 and XR-500 before 6.4 allows remote attackers to cause a permanent service interruption. The OSPF implementation incorrectly handles the number of LSA fields when other packet fields are modified, leaving the device in a persistent denial-of-service state. OSPF must be enabled, and receipt of a crafted OSPF packet can permanently interrupt network switching operations.

The record

CVE
CVE-2020-28393
Published
May 12, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-682, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 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

7.1NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:C
7.5NIST NVDCVSS:3.1/AV:N/AC:L/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.

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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-682Incorrect Calculation
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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