CVE-2026-98610
Description
A flaw was found in the Linux kernel's Hierarchical Fair Service Curve (HFSC) network packet scheduler. A local user with network administration privileges, such as within a user namespace, can exploit this flaw to cause a Denial of Service (DoS). Due to a lack of revalidation when traffic class levels are adjusted, conflicting filter configurations can create an infinite loop during packet classification. When network traffic traverses these cyclic rules, the system becomes unresponsive or crashes.
Statement
This vulnerability is rated as Moderate impact for Red Hat Enterprise Linux because triggering the denial of service requires local administrative capabilities—specifically network administration permissions, which unprivileged users can obtain only inside an unprivileged user namespace. The affected Hierarchical Fair Service Curve (HFSC) queuing discipline is not active by default and requires explicit traffic control configuration. Because the defect only results in a system hang or kernel panic without allowing unauthorized data access, modification, or privilege escalation, the severity does not rise to Important.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Amplification
An infinite loop will cause unexpected consumption of resources, such as CPU cycles or memory. The software's operation may slow down, or cause a long time to respond.
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