CVE-2026-14258
Description
A flaw was found in dhcpcd's IPv6 Neighbor Discovery Router Advertisement processing. A specially crafted IPv6 Router Advertisement containing a zero-length Neighbor Discovery option can bypass validation during packet storage and later be reparsed without adequate validation, causing the parser to enter a non-advancing loop. Successful exploitation may result in excessive CPU consumption, leading to a denial of service.
Statement
Red Hat Product Security has rated this vulnerability as Moderate. Exploitation requires an adjacent unauthenticated attacker to send a specially crafted IPv6 Router Advertisement from the same Layer-2 network segment to a system running dhcpcd with IPv6 Router Advertisement processing enabled. Because Router Advertisements are processed automatically by dhcpcd, no additional user interaction or prior authentication is required. Successful exploitation can cause dhcpcd to repeatedly process the malformed Router Advertisement, resulting in excessive CPU utilization and denial of service.
The root cause of this vulnerability is inconsistent validation during Router Advertisement processing. While malformed Neighbor Discovery options are detected during the initial parsing stage, a specially crafted packet may already have been retained for subsequent processing.
Earlier upstream release 75289ca (dhcpcd v10.2.0) addressed this by immediately discarding malformed Router Advertisements before they could be reparsed. Subsequent upstream changes (805fe4ac) further strengthened the implementation by validating all Neighbor Discovery options before storing the packet, improving the overall robustness of the parsing logic.
Only Red Hat Enterprise Linux 10 and Red Hat In Vehicle OS ships "dhcpcd". Both products are shipped with affected versions.
Mitigation
Until an updated package is available, administrators should disable IPv6 Router Advertisement processing on interfaces where it is not required or restrict acceptance of untrusted ICMPv6 Router Advertisements using appropriate network filtering.
Systems that rely on IPv6 Stateless Address Autoconfiguration (SLAAC) or Router Advertisement-based network configuration should carefully evaluate the operational impact before applying these mitigations.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 6.5 |
| Attack Vector | Adjacent Network | N/A | Adjacent Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:A/AC:L/PR:N/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.
Acknowledgements
Red Hat would like to thank AISLE Research for reporting this issue.
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