GHSA-h958-fxgg-g7w3 is a medium-severity (CVSS 5.9) vulnerability in OPCFoundation.NetStandard.Opc.Ua.Core. A fix is available for OPCFoundation.NetStandard.Opc.Ua.Core — see the affected versions and patch details below.
Security Update for the OPC UA .NET Standard Stack
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-h958-fxgg-g7w3.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-h958-fxgg-g7w3 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
OPCFoundation.NetStandard.Opc.Ua.CoreReal-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 security update resolves a vulnerability in the OPC UA .NET Standard Stack that allows an unauthorized attacker to bypass application authentication when the deprecated Basic128Rsa15 security policy is enabled.
Note that the Basic128Rsa15 is disabled by default so most users will not be affected. When this patch is applied the Server closes all channels using the Basic128Rsa15 if an attack is detected. This introduces a DoS before any compromise can occur which is preferable to a compromise. To prevent this failure, applications must stop using Basic128Rsa15.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | OPCFoundation.NetStandard.Opc.Ua.Core | all versions | 1.5.374.158dotnet add package OPCFoundation.NetStandard.Opc.Ua.Core --version 1.5.374.158 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for OPCFoundation.NetStandard.Opc.Ua.Core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update OPCFoundation.NetStandard.Opc.Ua.Core to 1.5.374.158 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h958-fxgg-g7w3 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-h958-fxgg-g7w3 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-h958-fxgg-g7w3. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-h958-fxgg-g7w3 in your dependencies?
O3 Security finds GHSA-h958-fxgg-g7w3 across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.