CVE-2021-27434

HIGH 7.5CVE-2021-27434 · Published 20/05/2021 · updated 17/06/2026

In short

CVE-2021-27434 is a HIGH (CVSS 7.5) vulnerability affecting .net based opc ua client/server sdk (unified-automation).
Chance of exploitation in the next 30 days (EPSS): 1.7%, higher than 77.8% of all vulnerabilities.
No patched version is listed yet: follow the vendor's advisory in References.

Package	Affected versions	Patched versions
.net based opc ua client/server sdk unified-automation	`≤ 3.0.7`	No fix yet

Description

Products with Unified Automation .NET based OPC UA Client/Server SDK Bundle: Versions V3.0.7 and prior (.NET 4.5, 4.0, and 3.5 Framework versions only) are vulnerable to an uncontrolled recursion, which may allow an attacker to trigger a stack overflow.

References

us-cert.cisa.gov/ics/advisories/icsa-21-133-04 · Third Party Advisory

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