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:

• Patch commit 0fb3b94a9431a3800717e5c3b6fa2e1045a15029
• Patch commit 4e10a730d1b511ff49723371ed6d694dd1b2c785
• Patch commit 7ae7b093b7dba9548a3bc4766b9364b97db4732d
• Patch commit 7b692dff8df0ba5feb8df00f27d906d6eb1fe627
• Patch commit 84419556359bc96d3fe1623d47a64c86542566cc
• Patch commit 9612d91f617231e03c49cb9b0c02f975a3b4f51f

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

# 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