CVE-2021-30195Network attack vector

Denial of service via buffer over-read

Published May 25, 2021 · Updated Aug 3, 2024

Improper input validation in CODESYS V2 runtime systems before 2.4.7.55 allows remote attackers to cause denial of service. The runtime communication server insufficiently validates a crafted client request before performing a buffer over-read. The controller processes the request only when no online password is configured or after successful authentication, and the resulting over-read interrupts the runtime service.

CVSS severity8.8
High
EPSS probability7.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in CODESYS V2 runtime systems before 2.4.7.55 allows remote attackers to cause denial of service. The runtime communication server insufficiently validates a crafted client request before performing a buffer over-read. The controller processes the request only when no online password is configured or after successful authentication, and the resulting over-read interrupts the runtime service.

The record

CVE
CVE-2021-30195
Published
May 25, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-125, CWE-20, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 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

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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

8.8CODESYS GmbHCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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 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-125Out-of-bounds Read
CWE-20Improper Input Validation
T0814Denial 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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