CVE-2026-58086: ktrace(2) privilege incorrectly validated in jails
As an inadvertent side effect of an unrelated code change, PRIVKTRACE was always denied to a jailed root user. Tracing configured by a jailed root user was therefore not flagged as privileged.
An unprivileged user in a jail that has permission to debug the target process can modify the jailed root user's ktrace(2) flags, or disable tracing outright. A jailed root user therefore cannot reliably trace unprivileged processes.
Affected Software
Event History
Frequently Asked Questions
Who can interfere with tracing configured by a jailed root user?
An unprivileged user within the same jail can do so if they have permission to debug the process being traced. They can modify the jailed root user's ktrace(2) flags or disable tracing entirely.
Does this let an unprivileged jail user trace arbitrary processes?
No. The described interference requires that the unprivileged user already has permission to debug the target process.
What is the operational impact for jailed root users?
A jailed root user cannot rely on ktrace(2) to trace unprivileged processes, because another eligible user in the jail can alter or stop that tracing.