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CVE Record

CVE-2021-29242: CODESYS Control Runtime system before 3.5.17.0 has improper input validation.

CODESYS Control Runtime system before 3.5.17.0 has improper input validation. Attackers can send crafted communication packets to change the router's addressing scheme and may re-route, add, remove or change low level communication packages.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-29242 affects CODESYS Control Runtime before 3.5.17.0. The issue could let an attacker use crafted communication packets to alter routing behavior inside the runtime communication layer. In industrial environments, that could disrupt or redirect controller communications. Public evidence does not show active exploitation or provide a CVSS score.

Executive priority

Prioritize this for OT environments using CODESYS-based controllers, especially where communication interfaces cross trust boundaries. There is no confirmed active exploitation in the supplied sources, but the potential to alter low-level communications makes delayed remediation risky for production reliability.

Technical view

The source describes improper input validation in CODESYS Control Runtime before 3.5.17.0. Crafted communication packets may change the router addressing scheme and re-route, add, remove, or change low-level communication packages. No CWE, CVSS vector, detailed affected CPEs, or exploit telemetry are provided in the bundle.

Likely exposure

Organizations may be exposed where CODESYS Control Runtime versions earlier than 3.5.17.0 are deployed, especially in OT networks where runtime communication paths are reachable. The provided affected-product metadata is incomplete, so asset owners must verify exact vendor-integrated runtime versions.

Exploitation context

The CVE description indicates packet-based manipulation of runtime routing behavior, but it does not provide exploit details. CISA KEV is false in the bundle, and no cited source confirms active exploitation. Treat internet-reachable or broadly reachable OT communication paths as higher concern.

Researcher notes

Evidence is sparse: the bundle provides a concise CVE description, a fixed-before version boundary, and vendor reference links, but no CVSS, CWE, affected CPEs, or technical advisory details. Avoid assuming OEM products are affected without confirming their embedded CODESYS runtime version.

Mitigation direction

  • Identify CODESYS Control Runtime deployments and versions.
  • Upgrade affected runtimes to 3.5.17.0 or later if vendor guidance supports it.
  • Check CODESYS and OEM advisories for product-specific update paths.
  • Restrict network access to runtime communication interfaces.
  • Monitor OT network paths for unexpected routing or communication changes.

Validation and detection

  • Inventory controllers and systems embedding CODESYS Control Runtime.
  • Confirm whether each runtime version is before 3.5.17.0.
  • Review OEM firmware advisories for bundled CODESYS versions.
  • Verify runtime communication interfaces are not internet-exposed.
  • Check logs or monitoring for unexplained routing changes.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2021-29242 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.