CVE-2026-51538
OpENer session-handle flaw allows access-control bypass via session reuse
Is CVE-2026-51538 being exploited?
Not confirmed. CVE-2026-51538 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 0.39% probability of exploitation in the next 30 days.
How severe is CVE-2026-51538?
CVE-2026-51538 is rated Critical with a CVSS score of 9.1. 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-2026-51538?
Yes. A fix has been recorded for CVE-2026-51538. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-51538 affect?
CVE-2026-51538 affects EIPStackGroup OpENer 2.3.0, EtherNet/IP devices using OpENer, Industrial control / embedded devices. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-51538?
Isolate affected devices, restrict EtherNet/IP (TCP 44818) access, apply vendor patch when released.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote access-control bypass: attacker reuses another client's session_handle to issue privileged encapsulation commands and control devices.
Immediate action required