CVE-2026-14258 in Red Hat
Summary
by MITRE • 07/01/2026
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.
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Analysis
by VulDB Data Team • 07/01/2026
This vulnerability resides in dhcpcd's handling of IPv6 Neighbor Discovery Router Advertisements which are fundamental components of ipv6 network communication protocols. The flaw specifically manifests when processing router advertisements containing zero-length Neighbor Discovery options that should normally trigger validation failures during initial packet parsing. When such malformed packets are accepted for storage without proper validation, they create a condition where subsequent reprocessing attempts fail to properly validate the packet structure, leading to a parser state where it repeatedly processes the same invalid data without making forward progress.
The technical mechanism behind this vulnerability involves a classic buffer over-read and parsing loop issue that occurs during the re-parsing phase of network packet processing. When dhcpcd encounters a zero-length option in an IPv6 Neighbor Discovery header, the initial validation logic may accept the packet despite the malformed structure, storing it in memory for later processing. During subsequent parsing operations, the parser fails to properly validate the zero-length option and enters a state where it continuously processes this invalid data without advancing through the packet structure, creating an infinite loop that consumes excessive cpu resources.
This vulnerability directly relates to CWE-129 Input Validation and CWE-691 Uncontrolled Resource Consumption, both of which are commonly exploited in denial of service scenarios. The operational impact extends beyond simple resource exhaustion as it can affect network connectivity for devices relying on dhcpcd for ipv6 address configuration. Systems that process large volumes of router advertisements or those operating in environments where malicious actors might inject crafted packets could experience complete service disruption, affecting not just individual hosts but potentially entire network segments that depend on proper ipv6 neighbor discovery functionality.
The attack surface is particularly concerning given that router advertisements are routinely transmitted across ipv6 networks and can be generated by any device claiming to be a legitimate router. This makes the vulnerability exploitable in various scenarios including man-in-the-middle attacks, network disruption campaigns, or simply through malformed packet injection during normal network operations. The lack of proper input validation during storage phase combined with inadequate reprocessing validation creates a persistent weakness that can be triggered by relatively simple crafted packets.
Mitigation strategies should focus on implementing proper input validation at both the initial packet acceptance and subsequent reprocessing phases. Network administrators should ensure dhcpcd is updated to versions containing patches that address this specific parsing loop condition, while also considering network segmentation and access control measures to limit exposure to potentially malicious router advertisements. The implementation of rate limiting for router advertisement processing and monitoring for unusual cpu consumption patterns can provide additional defense in depth measures against exploitation attempts targeting this vulnerability.
From an ATT&CK perspective, this vulnerability maps to T1499.004 Network Denial of Service and T1595.001 Network Configuration Discovery, as it enables attackers to disrupt network services while potentially gaining information about network topology through the manipulation of neighbor discovery protocols. The vulnerability demonstrates how seemingly minor parsing flaws in network stack components can have significant operational impacts on network availability and service delivery, emphasizing the importance of robust input validation in all network protocol implementations.