CVE-2026-72421
Description
A flaw was found in the Linux kernel. When the CONFIG_IP_MULTIPLE_TABLES option is enabled without additional routing rules, the fib_lookup() function can incorrectly process error routes. This allows an error route in the local or main routing tables to be overwritten by a default route. The consequence is inconsistent network behavior, potentially leading to a denial of service for affected network paths.
Statement
This vulnerability is rated as Low severity because exploitation requires local administrative network capabilities to manipulate routing tables, and the resulting impact is limited to incorrect path resolution rather than kernel panics or data leakage. In default Red Hat Enterprise Linux deployments, network setups typically configure explicit routing rules or rely on standard tables where this specific error route override does not occur during normal operations. Unprivileged users cannot configure or manipulate routing tables to trigger this behavior without elevated privileges.
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 | 10 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Changed |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | High | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
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