CVE-2021-27432

mediumpriority · track · 31EPSS 0.019 · 80 %ileDEEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.95% (80th) EPSS
CVSS 5 · medium
Is it mine?
60 products
Check your exposure
Who says so?
5 sources
cnnvd · enisa_euvd · fstec_bdu · beckhoff_psirt

EPSS · scored 2026-10-27

OPC Foundation UA .NET Standard versions prior to 1.4.365.48 and OPC UA .NET Legacy are vulnerable to an uncontrolled recursion, which may allow an attacker to trigger a stack overflow.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • Fixedbeckhoff_psirt

    Update to a recent version of the affected product and update the .NET Framework.

  • FixedOPC UA .NET Standardcisa_csaf_ot

    OPC Foundation recommends users install the OPC UA .NET Standard stack update.

    https://github.com/OPCFoundation/UA-.NETStandard/releases/tag/1.4.365.48
  • Mitigationbeckhoff_psirt

    Consider limiting access to the network communication ports of affected server products. Also consider limiting where the affected client products are allowed to connect to. For example, this can be achived with Windows' built-in firewall by incoming rules for servers and outgoing rules for clients. Consider to minimize the ability of an attacker to hijack communication establishment from a client to a server. For example this can be achieved with the help of zones and conduits: Try to keep servers and clients within the same network zone and prevent intrusion into that zone. Try to enclose communication establishment within conduits like VPN channels (where one conduit can serve for many OPC UA connections) and prevent attackers from intruding into such channels. Consider updating the .NET Framework.

  • MitigationAnalytiXcisa_csaf_ot

    Do not click web links or open unsolicited attachments in e-mail messages.

  • MitigationGENESIS64cisa_csaf_ot

    Do not click web links or open unsolicited attachments in e-mail messages.

  • MitigationHyper Historiancisa_csaf_ot

    Do not click web links or open unsolicited attachments in e-mail messages.

  • MitigationMC Works64cisa_csaf_ot

    Do not click web links or open unsolicited attachments in e-mail messages.

  • MitigationMobileHMIcisa_csaf_ot

    Do not click web links or open unsolicited attachments in e-mail messages.

02

cvss

Technical severity, 0–10. One row per scoring source.

7.5
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6
v3.07.5highCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · CISA US
v3.17.5highAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · Beckhoff PSIRT DE
v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-674USCWE-674USCWE-674USCWE-674US
04

affected products (60)

Products and version ranges known to be affected.

showing 20 of 60
05

advisories (3)

Vendor and ecosystem advisories describing this.

  • VDE-2021-008Beckhoff: Stack Overflow and XXE vulnerability in various OPC UA products2024-10-21csaf · beckhoff_psirtDE

    The affected products can act as OPC UA client or server and are vulnerable to two different kind of attacks via the OPC UA protocol. For both cases the attacker can send packets via the OPC UA protocol without the need to authenticate and 1. provoke a stack overflow resulting in denial of service of the product or 2. make the product disclose information to the attacker without authorization.

  • ICSA-21-133-03OPC Foundation UA Products Built with .NET Framework2021-05-13icsa · cisa_csaf_otUS

    Successful exploitation of this vulnerability could trigger a stack overflow.

  • ICSA-21-294-03ICONICS GENESIS64 and Mitsubishi Electric MC Works64 OPC UA2021-10-21icsa · cisa_csaf_otUS

    Successful exploitation of this vulnerability could trigger a stack overflow.

06

also known as (6)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bdubeckhoff_psirtcisa_csaf_otNVDCVE.orgMITRE
published 2021-05-20modified 2026-06-17
08

references (10)

External citations — patches, advisories, analysis.

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