CVE-2026-21655
Deserialization RCE in Johnson Controls Victor (Windows) affecting versions <3.0
Is CVE-2026-21655 being exploited?
Not confirmed. CVE-2026-21655 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 0.49% probability of exploitation in the next 30 days.
How severe is CVE-2026-21655?
CVE-2026-21655 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-2026-21655?
Yes. A fix has been recorded for CVE-2026-21655. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-21655 affect?
CVE-2026-21655 affects Johnson Controls Victor (Windows) versions >=2.9 and <3.0. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-21655?
Upgrade to Victor 3.0 or apply vendor patch; isolate and monitor affected hosts.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote arbitrary code execution via crafted serialized input, enabling full system compromise and lateral movement on affected Windows hosts.
Immediate action required
- affected< 3.2
- affected< 8.0
- affected< 4.1
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.