CVE-2026-98583 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
nfc: nfcmrvl: validate helper command length before pull
The firmware download receive path removes the NCI data header and reads the helper command before validating the remaining packet length. A short frame can therefore reach the data access before the malformed packet is rejected.
Validate the complete helper command length before stripping the NCI data header.
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Analysis
by VulDB Data Team • 10/18/2026
This vulnerability resides within the Linux kernel's Near Field Communication subsystem, specifically in the Marvell NFC driver known as nfcmrvl. The flaw involves a critical order-of-operations error during the firmware download process where the system attempts to parse incoming network control interface packets. In this specific code path, the implementation is designed to receive data from external hardware or connected devices and strip away protocol headers before processing the payload. However, the current logic incorrectly prioritizes extracting helper command information over verifying the integrity of the packet structure itself. This sequencing error creates a window where malformed or truncated frames can trigger memory access operations that occur prior to length validation checks.
The technical root cause is a classic out-of-bounds read condition resulting from insufficient input validation. When a short frame arrives, indicating that the data payload is shorter than expected for a valid command structure, the driver proceeds to remove the NCI data header and reads into what it assumes is a complete helper command buffer. Because the length check happens after this initial parsing step, the code may read beyond the allocated bounds of the packet buffer if the incoming frame is truncated or malformed. This behavior allows an attacker who can inject crafted NFC frames to cause the kernel to access memory locations outside the intended data structure. Such out-of-bounds reads typically result in information disclosure, where sensitive kernel memory contents are leaked through subsequent operations that utilize the corrupted pointer values or return invalid data to user space applications managing the NFC interface.
From an operational perspective, this vulnerability poses a significant risk to system stability and security integrity. While immediate exploitation for arbitrary code execution is less likely with a read-only flaw compared to write vulnerabilities, the ability to leak kernel memory addresses can facilitate further attacks by bypassing address space layout randomization protections. Furthermore, if the malformed data leads to undefined behavior in subsequent processing steps, it could potentially trigger a denial of service condition through kernel panics or system crashes. The impact is particularly relevant for devices relying on NFC connectivity for secure element interactions or firmware updates, as an attacker with physical proximity and the ability to send custom NFC commands could exploit this logic flaw without requiring prior authentication or elevated privileges on the host device.
To mitigate this risk, it is imperative that developers enforce strict validation of packet lengths before any structural parsing or header stripping occurs. The fix involves reordering the operations within the firmware download receive path so that the complete helper command length is verified against expected bounds immediately upon receipt of the frame. This ensures that malformed packets are rejected at the earliest possible stage, preventing any access to potentially invalid memory regions. System administrators should apply kernel updates that include this patch as soon as they become available through their distribution channels. Additionally, implementing defense-in-depth strategies such as enabling kmemleak for debugging and restricting NFC device permissions via mandatory access control policies can further reduce the attack surface associated with hardware interface vulnerabilities. This issue aligns with CWE-125 Out-of-bounds Read and is relevant to ATT&CK techniques involving data exfiltration from local systems through peripheral interfaces.