CVE-2026-98427

Red Hat Product Security has rated the security impact of this issue as Low for the affected products: the kernel and kernel-rt packages in Red Hat Enterprise Linux 7 and 8, and the RHEL CoreOS 8 kernel shipped in OpenShift Container Platform 4.12. The Red Hat Enterprise Linux 6, 9, and 10 kernels, the RHEL CoreOS 9 kernel used by later OpenShift Container Platform releases, and Red Hat In-Vehicle OS are not affected. A flaw was found in the Linux kernel's CoDel (Controlled Delay) packet scheduler (net/sched/codel), whose implementation is shared by the codel and fq_codel queueing disciplines. When a codel or fq_codel queue is configured with a very small interval, the CoDel control-law step between scheduled drops rounds down to zero, so the packet-dropping loop in codel_dequeue() never advances and instead drains the entire queue backlog while holding the qdisc lock. An unprivileged local user with the ability to set up such a queueing configuration (for example, by gaining CAP_NET_ADMIN within a user and network namespace) and to generate traffic through it can keep the CPU spinning in this loop, producing a kernel soft lockup that makes the system unresponsive. The issue affects availability only; there is no impact on confidentiality or integrity. The Red Hat CVSS base score is 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), with the Low impact rating reflecting the local attack vector, the prerequisite non-default queueing configuration, and the denial-of-service-only consequence. For the affected Red Hat Enterprise Linux 7 and 8 streams, delivery of a fix is currently deferred. The residual risk is a local denial of service: exploitation requires local access, the ability to configure a queueing discipline with a sub-tick interval, and sufficient queued traffic, and it does not cross privilege or trust boundaries or otherwise compromise the system.