CVE-2026-23315: Linux Kernel Buffer Overflow Vulnerability

CVE-2026-23315 Overview

A memory safety vulnerability has been identified in the Linux kernel's mt76 wireless driver, specifically within the mt76_connac2_mac_write_txwi_80211() function. The flaw allows for a possible out-of-bounds (OOB) memory access when processing management frame fields without proper length validation. This vulnerability affects systems using MediaTek MT76 wireless chipsets and could potentially lead to kernel memory corruption or information disclosure.

Critical Impact
An out-of-bounds memory access in the kernel WiFi driver could allow attackers to read or write kernel memory, potentially leading to denial of service, information disclosure, or privilege escalation on affected Linux systems.

Affected Products

Linux Kernel (multiple stable branches affected)
Systems using MediaTek MT76 wireless chipsets (mt76 driver)
Wireless access points and routers running affected kernel versions

Discovery Timeline

2026-03-25 - CVE-2026-23315 published to NVD
2026-03-25 - Last updated in NVD database

Technical Details for CVE-2026-23315

Vulnerability Analysis

The vulnerability resides in the mt76_connac2_mac_write_txwi_80211() function within the mt76 wireless driver subsystem of the Linux kernel. The function processes 802.11 management frames but fails to properly validate frame length before accessing management frame fields. Specifically, the code accesses mgmt->u.action.u.addba_req.capab without first verifying that the frame buffer contains sufficient data to safely read these nested structure fields.

This lack of boundary checking creates an out-of-bounds read condition where the driver may attempt to access memory beyond the actual frame data. In kernel context, this type of memory safety issue is particularly serious as it operates with elevated privileges and could potentially be triggered by specially crafted wireless frames.

Root Cause

The root cause of this vulnerability is insufficient input validation in the WiFi frame processing code. The mt76_connac2_mac_write_txwi_80211() function directly accesses management frame structure fields without first verifying that the frame length is adequate to contain those fields. The fix implements proper length checks before accessing the mgmt fields to ensure the frame buffer has sufficient data to safely read the targeted structure members, including the addba_req.capab field within the action frame union.

Attack Vector

An attacker could potentially exploit this vulnerability by sending specially crafted 802.11 management frames to a system running the vulnerable mt76 driver. The attack would require the attacker to be within wireless range of the target system or have the ability to inject wireless frames into the communication channel. When the vulnerable function processes a malformed frame with insufficient length, it may read memory beyond the intended buffer boundaries.

The fix adds frame length validation before accessing management fields in mt76_connac2_mac_write_txwi_80211(). The patch ensures the code checks the frame length is adequate before attempting to read mgmt->u.action.u.addba_req.capab and other nested structure fields. For complete technical details, refer to the kernel git commit.

Detection Methods for CVE-2026-23315

Indicators of Compromise

Unexpected kernel crashes or panics related to the mt76 wireless driver module
Kernel log messages indicating memory access violations in WiFi subsystem functions
Unusual wireless management frame activity targeting affected systems
System instability when processing 802.11 management frames

Detection Strategies

Monitor kernel logs for oops or panic messages referencing mt76_connac2_mac_write_txwi_80211 or related mt76 driver functions
Deploy intrusion detection rules to identify malformed 802.11 management frames with abnormal length parameters
Use kernel memory debugging tools (KASAN, KMSAN) to detect out-of-bounds memory accesses during testing
Implement wireless IDS to monitor for suspicious action frame patterns

Monitoring Recommendations

Enable kernel address sanitizer (KASAN) in development and testing environments to catch memory safety issues
Configure wireless network monitoring to alert on unusual management frame patterns
Review system logs regularly for mt76 driver-related error messages
Implement centralized logging for kernel messages across all affected systems

How to Mitigate CVE-2026-23315

Immediate Actions Required

Update the Linux kernel to a patched version that includes the frame length validation fix
Review systems for any signs of exploitation or unusual wireless driver behavior
Consider temporarily disabling affected wireless interfaces on critical systems until patches are applied
Prioritize patching for systems in untrusted wireless environments

Patch Information

Linux kernel maintainers have released patches to address this vulnerability across multiple stable kernel branches. The fix adds proper length validation before accessing management frame fields in mt76_connac2_mac_write_txwi_80211(). Patches are available through the official kernel git repositories:

Workarounds

If patching is not immediately possible, consider disabling the mt76 wireless driver on systems where it is not essential
Implement network segmentation to limit wireless exposure of critical systems
Use alternative wireless drivers or hardware if available for critical infrastructure
Monitor affected systems closely for signs of exploitation until patches can be applied

bash

# Check if the mt76 driver is loaded on your system
lsmod | grep mt76

# If mitigation is needed, the driver can be temporarily unloaded
# WARNING: This will disable WiFi functionality on systems using MT76 chipsets
sudo modprobe -r mt76_connac_lib
sudo modprobe -r mt76

# To prevent the module from loading at boot (temporary workaround)
echo "blacklist mt76" | sudo tee /etc/modprobe.d/mt76-blacklist.conf