CVE-2026-64273 in Linux
Summary
by MITRE • 07/25/2026
In the Linux kernel, the following vulnerability has been resolved:
Input: iforce - bound the device-reported force-feedback effect index
iforce_process_packet() handles a status report (packet id 0x02) by taking a force-feedback effect index straight from the device wire and using it to address the per-effect state array:
i = data[1] & 0x7f;
if (data[1] & 0x80) {
if (!test_and_set_bit(FF_CORE_IS_PLAYED, iforce->core_effects[i].flags))
... } else if (test_and_clear_bit(FF_CORE_IS_PLAYED, iforce->core_effects[i].flags)) {
... }
The index is masked only with 0x7f, so it ranges 0..127, but core_effects[] holds only IFORCE_EFFECTS_MAX (32) entries. For an index
of 32..127 the test_and_set_bit()/test_and_clear_bit() is an out-of-bounds single-bit read-modify-write past the array. core_effects[]
is the second-to-last member of struct iforce, so the write lands in the trailing members and beyond the embedding kzalloc()'d iforce_serio / iforce_usb object.
data[1] is unvalidated device payload on both transports (the USB
interrupt endpoint and serio), and the status path is not gated on force feedback being present, so a malicious or counterfeit device can set or clear a bit at an attacker-chosen offset past the object.
Reject an out-of-range index instead of indexing with it. Bound against the array dimension IFORCE_EFFECTS_MAX rather than dev->ff->max_effects so the check guarantees memory safety regardless of how many effects the device registered. A legitimate "effect started/stopped" status always carries an index below IFORCE_EFFECTS_MAX, so well-formed devices are unaffected; the neighbouring mark_core_as_ready() loop is already bounded and is left untouched.
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Analysis
by VulDB Data Team • 07/25/2026
The vulnerability in question resides within the linux kernel's iforce subsystem which handles force-feedback effects for certain gaming devices through both usb and serio interfaces. This flaw represents a classic out-of-bounds memory access issue that can lead to arbitrary code execution or system instability. The problem manifests when processing status reports from peripheral devices, specifically packets with id 0x02 that contain force-feedback effect index information directly from the device wire.
The technical implementation flaw occurs in the iforce_process_packet() function where the code extracts an effect index from data[1] and applies a bitwise mask of 0x7f to obtain values between 0 and 127. However, the core_effects array is statically allocated with only IFORCE_EFFECTS_MAX entries (typically 32), creating a clear mismatch between the potential index range and actual array bounds. This discrepancy allows attackers to traverse memory beyond the intended array boundaries through single-bit read-modify-write operations.
When an out-of-bounds index is processed, the test_and_set_bit() and test_and_clear_bit() operations target memory locations that extend past the core_effects array into adjacent memory regions. Since core_effects is positioned near the end of the iforce structure which is allocated via kzalloc(), these operations can overwrite critical data structures or metadata belonging to the iforce_serio or iforce_usb objects. The memory corruption occurs at arbitrary offsets determined by the attacker-controlled index value, potentially leading to privilege escalation, denial of service, or code execution.
This vulnerability directly maps to CWE-129 and CWE-787 within the Common Weakness Enumeration framework, representing insufficient input validation and out-of-bounds read/write conditions respectively. The attack surface is particularly concerning as it operates at the kernel level without requiring user interaction beyond device connection, making it exploitable through malicious or counterfeit hardware devices. The ATT&CK framework categorizes this under privilege escalation techniques where adversaries leverage kernel vulnerabilities to gain elevated system access.
The exploitation potential arises from the fact that both USB interrupt endpoints and serio interfaces accept unvalidated device payloads, with no gating mechanism preventing status processing when force feedback is not properly initialized. This means an attacker-controlled device can manipulate memory layout by setting or clearing bits at chosen offsets beyond the legitimate object boundaries. The fix implemented requires rejecting out-of-range indices before any memory operations occur, specifically bounding against IFORCE_EFFECTS_MAX rather than device-reported effect counts to guarantee memory safety regardless of device capabilities.
Mitigation strategies must focus on input validation and bounds checking within kernel subsystems handling external device communications. The solution involves implementing proper index validation that ensures all array accesses remain within defined boundaries while maintaining compatibility with legitimate device operations. This approach aligns with secure coding practices recommended by both the linux kernel security team and industry best practices for preventing memory corruption vulnerabilities in device drivers. The neighboring mark_core_as_ready() function remains untouched as it already implements appropriate bounds checking, demonstrating the targeted nature of this specific fix rather than a broad architectural change.