CVE-2026-23124
Description
A flaw was found in the Linux kernel's IPv6 neighbor discovery component. A remote attacker on an adjacent network can exploit a data race in the ndisc_router_discovery function by sending specially crafted Internet Control Message Protocol version 6 (ICMPv6) Router Advertisement (RA) messages. This allows for inconsistent updates to the ra_mtu value, leading to transient or incorrect Maximum Transmission Unit (MTU) state and spurious interface information notifications. The primary impact is limited availability of the affected system.
Statement
A data race exists in IPv6 neighbor discovery because ndisc_router_discovery can read and write in6_dev ra_mtu without holding a lock while processing Router Advertisement MTU options. Under concurrent RA processing the ra_mtu value can be observed and updated inconsistently which can result in transient or incorrect MTU state and spurious ifinfo notifications. For the CVSS the PR is N because the input comes from ICMPv6 Router Advertisements and does not require local privileges on the target. The issue is network reachable in an adjacent network because RA traffic is typically limited to the local link. Realistic impact is limited availability and configuration stability rather than a direct kernel crash.
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 | 5.9 | 5.5 | N/A |
| Attack Vector | Network | Local | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | None | 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:N/AC:H/PR:N/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: Resource Consumption (Other)
When a race condition makes it possible to bypass a resource cleanup routine or trigger multiple initialization routines, it may lead to resource exhaustion.
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Instability
When a race condition allows multiple control flows to access a resource simultaneously, it might lead the product(s) into unexpected states, possibly resulting in a crash.
Confidentiality,Integrity
Technical Impact: Read Files or Directories; Read Application Data
When a race condition is combined with predictable resource names and loose permissions, it may be possible for an attacker to overwrite or access confidential data (CWE-59).
Access Control
Technical Impact: Execute Unauthorized Code or Commands; Gain Privileges or Assume Identity; Bypass Protection Mechanism
This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider.
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