CVE-2026-23276
Description
A flaw was found in the Linux kernel. When a bond device in broadcast mode has Generic Routing Encapsulation (GRE) tap interfaces configured as slaves, and these GRE tunnels are routed back through the bond, multicast or broadcast network traffic can trigger an infinite recursion. This recursion occurs within the kernel's tunnel transmit functions, leading to a kernel stack overflow. A local attacker could potentially exploit this to cause a Denial of Service (DoS) on the system.
Statement
This vulnerability requires a specific network configuration: a bonding device in broadcast mode with GRE tap tunnel slaves where the tunnels route back through the bond. When multicast or broadcast traffic is sent, the lack of recursion limits in tunnel transmit functions causes infinite recursion between bond_xmit_broadcast() and tunnel xmit functions, exhausting the kernel stack. This affects GRE, VXLAN, Geneve, and similar tunnels.
Mitigation
Avoid configuring bond devices in broadcast mode with tunnel interfaces (GRE, VXLAN, Geneve) as slaves when those tunnels route back through the bond. Alternatively, use a different bonding mode such as active-backup or 802.3ad.
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 | 5.5 | 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 | None | N/A |
| Integrity Impact | None | None | 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: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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