CVE-2026-98541
Description
A flaw was found in the Linux kernel's Foo-over-UDP (FOU) networking subsystem. When configuring a direct encapsulation tunnel without specifying the required network protocol attribute, the kernel permits tunnel socket creation with an uninitialized protocol value. Consequently, incoming network packets processed by this socket are never released from memory. An attacker can exploit this flaw by sending network traffic to the affected tunnel port to continuously leak kernel memory, resulting in a Denial of Service (DoS) due to memory exhaustion.
Statement
Moderate severity is assigned to this vulnerability because creating the vulnerable direct encapsulation tunnel requires local administrative network capabilities (such as CAP_NET_ADMIN or an unprivileged user namespace), preventing direct unprivileged or remote triggering. In default Red Hat Enterprise Linux deployments, Foo-over-UDP tunnels are not configured or active. Consequently, exploitation is restricted to environments where untrusted users can manage network namespaces or where direct encapsulation FOU tunnels have been explicitly established.
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 (Other); DoS: Resource Consumption (Memory); DoS: Resource Consumption (CPU)
An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Frequently Asked Questions
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