CVE-2026-23300
Description
A flaw was found in the Linux kernel's IPv6 networking stack. When a standalone IPv6 nexthop object is created with a loopback device, it is misclassified as a reject route, leading to an unallocated pointer. If an IPv4 route then attempts to reference this nexthop, it causes a NULL pointer dereference. This can result in a kernel panic, leading to a denial of service (DoS) for the system.
Statement
This flaw affects systems using advanced routing features with IPv6 nexthop objects on loopback devices. The misclassification causes nhc_pcpu_rth_output to remain unallocated, leading to a panic when IPv4 routes reference the nexthop. Triggering this requires specific routing configuration with nexthop objects on loopback, which is uncommon in typical deployments.
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)
Confidentiality
Technical Impact: Read Memory; Read Application Data
When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The uninitialized resource may contain values that cause program flow to change in ways that the programmer did not intend.
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