CVE-2026-12366
Use-after-free in Zephyr kernel timer enables user-to-kernel privilege escalation.
Is CVE-2026-12366 being exploited?
Not confirmed. CVE-2026-12366 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 0.12% probability of exploitation in the next 30 days.
How severe is CVE-2026-12366?
CVE-2026-12366 is rated High with a CVSS score of 8.8. 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-2026-12366?
Yes. A fix has been recorded for CVE-2026-12366. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-12366 affect?
CVE-2026-12366 affects Zephyr RTOS kernel (userspace + dynamic objects), Devices built with CONFIG_USERSPACE and CONFIG_DYNAMIC_OBJECTS. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-12366?
Apply Zephyr patch/update immediately; or disable CONFIG_DYNAMIC_OBJECTS/CONFIG_USERSPACE until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Deterministic kernel use-after-free on k_timer expiry causes memory corruption in ISR, enabling local privilege escalation from unprivileged user threads.
Immediate action required
- affected>= 1.12.0 and < 4.5.0
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.