CVE-2026-23359
Description
A flaw was found in the Linux kernel. The get_upper_ifindexes() function, which collects network device indices, fails to check array boundaries when writing these indices. This allows a local attacker to create a large number of virtual network interfaces (macvlans), causing a stack-out-of-bounds write. The consequence is a denial of service (DoS), as the system aborts network packet redirection, affecting network availability.
Statement
This flaw affects systems using XDP (eXpress Data Path) with BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS on devices with many upper interfaces (>8 macvlans). The stack buffer overflow occurs because MAX_NEST_DEV assumption doesn't hold for all configurations. Requires ability to create many macvlan interfaces and attach XDP programs.
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 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | High | N/A |
| Integrity Impact | None | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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