CVE-2026-98019

A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) verifier. The verifier failed to mark scalar registers as precise when checking null function arguments and specific helper call parameters, causing its state-tracking logic to improperly prune verification paths. A local attacker with permission to load BPF programs could exploit this flaw using a specially crafted program to bypass safety checks, potentially leading to privilege escalation or a denial of service.

A Moderate severity flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) verifier, affecting the kernel and kernel-rt packages in Red Hat Enterprise Linux 8, 9, and 10, the kernels in Red Hat In-Vehicle OS 2, and the RHEL CoreOS 8/9 kernels shipped with OpenShift Container Platform 4. The verifier's check_func_arg() accepted nullable (NULL) function arguments, and check_helper_call() enforced that the second parameter of bpf_get_local_storage() be zero, without marking the underlying scalar register as precise. As a result, a verifier state checkpoint created on such a path could prune verification against an arbitrary scalar value, allowing a specially crafted BPF program that should have been rejected to pass verification. Exploitation requires local access with permission to load BPF programs; it can lead to a denial of service, and potentially to privilege escalation if the verifier bypass is turned into a memory-safety violation. Red Hat's CVSS 3.1 score of 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) reflects the demonstrated availability impact, as no concrete confidentiality or integrity primitive has been demonstrated for this issue. Red Hat Enterprise Linux 6 and 7 Extended Lifecycle Support are not affected because the vulnerable code is not present in those kernels. Fixes for the affected streams are currently deferred to future maintenance updates; the residual risk is limited to local attackers who already have the ability to load BPF programs.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

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