CVE-2026-80814 in Linux
Summary
by MITRE • 09/04/2026
In the Linux kernel, the following vulnerability has been resolved:
rndis_host: add overflow check in rndis_rx_fixup()
Add an overflow check to ensure that data_offset + data_len + 8 does not wrap, which would enable an OOB read of the USB data buffer.
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Analysis
by VulDB Data Team • 09/05/2026
The Linux kernel's RNDIS (Remote Network Driver Interface Specification) host driver contains a critical integer overflow vulnerability within the rndis_rx_fixup function, specifically involving the calculation of memory offsets for processing incoming network packets over USB connections. This flaw arises when the system attempts to determine the position and length of data segments within an RNDIS message buffer without adequately validating that the sum of the current offset, the declared data length, and a fixed header size will not exceed the bounds of the allocated buffer or wrap around due to integer arithmetic limitations. In C-based kernel code, unsigned integer overflow is particularly dangerous because it can result in a significantly smaller calculated value than intended, effectively bypassing subsequent boundary checks that rely on these computed values.
The technical root cause lies in the lack of explicit validation before performing addition operations involving data_offset and data_len variables derived from network packet headers. When an attacker or malicious device sends a crafted USB RNDIS packet with specific combinations of offset and length fields, the arithmetic operation data_offset + data_len + 8 can wrap around to a small positive number if it exceeds the maximum value representable by the integer type used for these calculations. This wrapped value is then used as an index or limit in subsequent memory access operations, leading to out-of-bounds reads where the kernel attempts to read from addresses outside the legitimate bounds of the USB data buffer allocated for that packet processing routine.
The operational impact of this vulnerability allows a local attacker with physical access to a vulnerable system via a malicious USB device, such as a BadUSB implementation or a compromised peripheral, to trigger an out-of-bounds memory read. While primarily classified as a denial-of-service risk due to potential kernel panics resulting from accessing invalid memory pages, the ability to perform arbitrary reads can also facilitate information disclosure attacks. By carefully crafting input packets, an attacker might be able to leak sensitive kernel memory contents, including cryptographic keys or other privileged data structures residing in adjacent memory regions, thereby compromising system confidentiality and integrity.
This vulnerability aligns with Common Weakness Enumeration CWE-190, which describes integer overflow or wraparound errors that lead to subsequent security weaknesses such as buffer overflows or out-of-bounds accesses. From a tactical perspective, the exploitation vector corresponds to ATT&CK technique T1205.008, specifically Supply Chain Compromise via Hardware Components, where an attacker leverages physical access through USB devices to execute malicious code or extract data from the target system. The vulnerability highlights the critical importance of rigorous input validation in network protocol implementations within the kernel space, particularly for interfaces that are frequently exposed to external hardware peripherals.
Mitigation strategies primarily involve applying the upstream Linux kernel patch that introduces explicit overflow checks before performing arithmetic operations on buffer offsets and lengths. System administrators should ensure their systems are updated with the latest stable kernel versions containing this fix. Additionally, organizations relying on USB-connected devices in secure environments should implement strict device control policies to prevent unauthorized peripherals from connecting to critical infrastructure. For developers maintaining custom RNDIS implementations or similar network drivers, it is essential to validate all length and offset fields against buffer sizes using safe arithmetic functions that detect overflow conditions before proceeding with memory access operations, thereby preventing the exploitation of integer wraparound flaws in low-level system code.