CVE-2021-34595Network attack vector

Memory corruption via invalid pointer offsets

Published Oct 26, 2021 · Updated Sep 17, 2024

Out-of-range pointer offsets in CODESYS GmbH V2 runtime components before 2.4.7.56 allow remote attackers to corrupt memory or crash controllers. The controller communication server accepts crafted requests containing invalid offsets and uses them for out-of-bounds reads or writes. Requests reach the vulnerable code only when no level 1 online password is configured or after authentication; exploitation can stop runtime operation or corrupt local memory.

CVSS severity8.1
High
EPSS probability0.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-range pointer offsets in CODESYS GmbH V2 runtime components before 2.4.7.56 allow remote attackers to corrupt memory or crash controllers. The controller communication server accepts crafted requests containing invalid offsets and uses them for out-of-bounds reads or writes. Requests reach the vulnerable code only when no level 1 online password is configured or after authentication; exploitation can stop runtime operation or corrupt local memory.

The record

CVE
CVE-2021-34595
Published
Oct 26, 2021
Updated
Sep 17, 2024
Vendor
CODESYS GmbH
Product
CODESYS Development System V2.3
Classifications
CWE-823, CAPEC-129, T0814
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=PLCWinNT <V2.4.7.56
  2. Affected versionversion=Runtime Toolkit 32 bit full <V2.4.7.56

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

CODESYS GmbH · CODESYS Development System V2.3version=PLCWinNT <V2.4.7.56; version=Runtime Toolkit 32 bit full <V2.4.7.56

Published CVSS scores

8.1CODESYS GmbHCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-823Use of Out-of-range Pointer Offset
CAPEC-129Pointer Manipulation
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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