CVE-2026-63362
Unsigned integer underflow in open62541 PubSub allows remote DoS via UDP
Is CVE-2026-63362 being exploited?
Not confirmed. CVE-2026-63362 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 1.5% probability of exploitation in the next 30 days.
How severe is CVE-2026-63362?
CVE-2026-63362 is rated High with a CVSS score of 8.2. 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-2026-63362?
Not known from our data. No patch reference has been recorded for CVE-2026-63362, 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-2026-63362 affect?
CVE-2026-63362 affects open62541 library, OPC UA PubSub implementations using open62541. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-63362?
Apply vendor patch when released; restrict/block UDP access to OPC UA endpoints and network-filter PubSub traffic.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote denial-of-service: crafted UDP packets trigger an unsigned integer underflow, crashing or disrupting OPC UA PubSub services.
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.