Security readout for executives and security teams
Plain-English summary
This vulnerability affects older CODESYS V2 runtime components used in industrial control environments. A malformed request can crash the runtime or overwrite local memory, creating operational disruption risk for systems that depend on these runtimes.
Executive priority
Treat this as high priority for industrial environments because exploitation could disrupt operations or alter local memory on affected runtime systems. Prioritize exposed and production-critical deployments first.
Technical view
CVE-2021-34595 is an out-of-bounds read/write issue tied to invalid offsets in CODESYS V2 Runtime Toolkit 32 Bit full and PLCWinNT before V2.4.7.56. CVSS 3.1 rates it 8.1, network-accessible with low privileges, impacting integrity and availability.
Likely exposure
Exposure is most likely where CODESYS V2 Runtime Toolkit 32 Bit full or PLCWinNT versions before V2.4.7.56 are deployed, especially on reachable engineering or control networks.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. The CVSS vector indicates network reachability and low privileges, but no exploit procedure or weaponized evidence is provided.
Researcher notes
Evidence is limited to the CVE record and CODESYS reference. Avoid broad product assumptions beyond Runtime Toolkit 32 Bit full and PLCWinNT before V2.4.7.56. The weakness is mapped to CWE-823.
Mitigation direction
- Upgrade affected CODESYS V2 runtime components to V2.4.7.56 or later.
- Check the CODESYS advisory for product-specific remediation guidance.
- Restrict runtime access to required engineering and control network segments.
- Remove unnecessary network exposure to affected runtime services.
- Prioritize patching systems supporting safety, production, or availability-critical operations.
Validation and detection
- Inventory hosts running CODESYS V2 Runtime Toolkit 32 Bit full or PLCWinNT.
- Verify installed runtime versions are V2.4.7.56 or newer.
- Confirm affected services are not reachable from untrusted networks.
- Review runtime and host logs for unexplained crashes or availability events.
- Validate compensating access controls for systems awaiting upgrade.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-823: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-34595 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
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.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H2.85.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16878&token=e5644ec405590e66aefa62304cb8632df9fc9e9c&download=CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use of Out-of-range Pointer Offset
Use of Out-of-range Pointer Offset represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.