kernel: kernel: Denial of Service via fprobe use-after-free (CVE-2026-98861)

Overview

A flaw was found in the Linux kernel's function probe (fprobe) tracing mechanism. When handlers execute during inactive Read-Copy Update (RCU, a kernel synchronization mechanism) states, unregistration routines fail to wait for active handlers to complete before freeing memory. A privileged local attacker could exploit this flaw to trigger a use-after-free condition, leading to a Denial of Service (DoS) or potentially arbitrary code execution.

Vendor advisories

• Red Hat VEX · Moderate · affected: Red Hat Enterprise Linux 10 · no fix planned: Red Hat Enterprise Linux 10 · updated 2026-10-21 · vex

kernel: kernel: Denial of Service via fprobe use-after-free — rated Moderate by Red Hat. Released 2026-10-18, updated 2026-10-21.

Affected:

• Red Hat Enterprise Linux 10

No fix planned:

• Red Hat Enterprise Linux 10

Remediation

Fix deferred

Workarounds / mitigations:

• Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.