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.NET
.NET NuGet
Not in CISA KEV
HIGH severity

CVE-2020-8867 — OPCFoundation.NetStandard…

HIGH

CVE-2020-8867 is a high-severity (CVSS 7.5) CWE-367 vulnerability in OPCFoundation.NetStandard.Opc.Ua. A fix is available for OPCFoundation.NetStandard.Opc.Ua — see the affected versions and patch details below.

Insufficient Session Expiration and TOCTOU Race Condition in OPC FOundation UA .Net Standard

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.6%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs85th percentile — riskier than 85% of all scored CVEsHighest risk
1.22%1.86%2.50%3.14%1.7%2.6%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-8867 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
.NETOPCFoundation.NetStandard.Opc.Ua

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

This vulnerability allows remote attackers to create a denial-of-service condition on affected installations of OPC Foundation UA .NET Standard 1.04.358.30. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of sessions. The issue results from the lack of proper locking when performing operations on an object. An attacker can leverage this vulnerability to create a denial-of-service condition against the application. Was ZDI-CAN-10295.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetOPCFoundation.NetStandard.Opc.Uaall versions1.4.359.31dotnet add package OPCFoundation.NetStandard.Opc.Ua --version 1.4.359.31

Affected Products

1 product · 1 configurations
Application
unified architecture .net-standardopcfoundation
≤ 1.04.358.30
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for OPCFoundation.NetStandard.Opc.Ua, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update OPCFoundation.NetStandard.Opc.Ua to 1.4.359.31 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-8867 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

This vulnerability allows remote attackers to create a denial-of-service condition on affected installations of OPC Foundation UA .NET Standard 1.04.358.30. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of sessions. The issue results from the lack of proper locking when performing operations on an object. An attacker can leverage this vulnerability to create a denial-of-service condition against the application. Was ZDI-CAN-10295.
O3 Security · Impact-Aware SCA

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CVE-2020-8867: OPCFoundation — Fixed in 1.4.359.31