CVE-2026-65423
Integer overflow in open62541 UA_Variant arrayDimensions may cause out-of-bounds write.
Is CVE-2026-65423 being exploited?
Not confirmed. CVE-2026-65423 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.60% probability of exploitation in the next 30 days.
How severe is CVE-2026-65423?
CVE-2026-65423 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-65423?
Not known from our data. No patch reference has been recorded for CVE-2026-65423, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-65423 affect?
CVE-2026-65423 affects open62541 (OPC UA library), Applications using open62541 (OPC UA servers/clients), Industrial control systems embedding open62541. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-65423?
Update to a patched open62541 release when available; restrict/untrusted OPC UA traffic and apply input validation.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attacker can craft OPC UA messages to trigger an OOB write, enabling crashes or potential remote code execution on affected components.
Patch when possible
- affected>= 1.3.0 and <= 1.3.17
- affected>= 1.4.0 and <= 1.4.16
- affected>= 1.5.0 and <= 1.5.4
- affectedmaster
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.