CVE-2026-97540 in Linux
Summary
by MITRE • 09/25/2026
In the Linux kernel, the following vulnerability has been resolved:
net: usb: pegasus: don't rely on id table pointer arithmetic
The current code is broken when dynamic ID is involved; in such cases usb_device_id parameter of probe lives on the heap and the pointer arithmetic will get an index that is wildly out of bound. Instead of keeping a side table for additional information, use driver_info field of the usb_device_id.
The dynamic ID parsing code needs to be updated for this; convert it to just write to the reserved entry for dynamic ID and remove the weird loop.
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Analysis
by VulDB Data Team • 09/25/2026
The Linux kernel vulnerability identified in the pegasus USB network driver stems from an unsafe implementation detail regarding how device identifiers are processed during the probe phase of driver initialization. The core technical flaw involves incorrect pointer arithmetic applied to a usb_device_id structure when dynamic IDs are utilized by users or system administrators at runtime. In standard static configurations, these structures reside within fixed memory segments where relative addressing is predictable and safe. However, when dynamic ID injection occurs, the usb_device_id parameter passed to the probe function resides on the heap rather than in a statically allocated array. The existing code logic assumes that pointer arithmetic will correctly index into an adjacent side table containing additional device information. Because the dynamically allocated structure does not maintain this contiguous memory layout with the expected metadata tables, the resulting index calculation points to arbitrary and out-of-bounds memory locations. This represents a classic instance of improper input validation leading to invalid memory access, specifically categorized under CWE-125 Out-of-bounds Read or potentially CWE-787 Out-of-bounds Write if the logic attempts to modify data at that corrupted address.
The operational impact of this vulnerability is significant due to its potential for causing kernel instability and security breaches. When the driver executes pointer arithmetic on a heap-based structure, it reads from memory addresses that are not owned by the intended context. This can lead to information disclosure if sensitive kernel data residing in adjacent memory pages is read and inadvertently exposed through subsequent network operations or error handling paths. More critically, depending on how the retrieved value is used within the driver logic, this out-of-bounds access could trigger a null pointer dereference or general protection fault, resulting in a denial of service by crashing the entire system. In worst-case scenarios where the corrupted index leads to writing data to an unintended memory location, it opens the door for arbitrary code execution with kernel privileges, allowing an attacker who can control the dynamic ID injection process to compromise the integrity and confidentiality of the host operating system.
To mitigate this vulnerability, the Linux kernel maintainers have refactored the pegasus driver to eliminate reliance on fragile pointer arithmetic and side tables. The solution involves leveraging the existing driver_info field within the usb_device_id structure itself to store necessary device-specific information rather than relying on external memory layouts that assume static allocation contexts. This approach aligns with standard USB subsystem practices where metadata is encapsulated directly within the identification structure, ensuring consistency regardless of whether the ID table is statically defined or dynamically generated at runtime. The dynamic ID parsing code was also updated to write exclusively to a reserved entry designated for dynamic IDs, removing complex and error-prone loop logic that previously attempted to manage memory offsets manually. This change not only resolves the immediate out-of-bounds access issue but also improves code maintainability by adhering to established kernel coding standards. From an ATT&CK perspective, this vulnerability relates to techniques involving exploitation of software vulnerabilities for privilege escalation or denial of service, specifically targeting resource management errors in operating system components. System administrators should ensure that their Linux kernels are updated with the patched version of the pegasus driver to prevent potential exploitation through maliciously crafted USB device identification sequences.