CVE-2026-22978: Linux Kernel Information Disclosure Flaw

CVE-2026-22978 Overview

CVE-2026-22978 is a kernel information disclosure vulnerability in the Linux kernel's WiFi subsystem. The vulnerability exists in the handling of struct iw_point, which contains a 32-bit memory hole on 64-bit architectures. This uninitialized memory gap can leak sensitive kernel data to user space when the structure is passed during wireless extension (WEXT) ioctl operations.

Critical Impact

This vulnerability allows unprivileged local users to potentially obtain 32 bits of kernel memory contents, which could include sensitive information such as kernel addresses or other security-relevant data.

Affected Products

• Linux kernel (multiple versions)
• 64-bit Linux distributions with WiFi/wireless extension support
• Systems using the legacy wireless extensions (WEXT) interface

Discovery Timeline

• 2026-01-23 - CVE CVE-2026-22978 published to NVD
• 2026-01-26 - Last updated in NVD database

Technical Details for CVE-2026-22978

Vulnerability Analysis

The vulnerability stems from improper memory initialization in the Linux kernel's wireless extensions subsystem. The struct iw_point structure is used to pass data between kernel space and user space during wireless ioctl operations. On 64-bit architectures, this structure contains a natural alignment gap (padding) between its members that creates a 32-bit "hole" in memory.

The structure layout reveals the issue:

struct iw_point {
  void __user   *pointer;       /* Pointer to the data (in user space) */
  __u16         length;         /* number of fields or size in bytes */
  __u16         flags;          /* Optional params */
};

On 64-bit systems, the void __user *pointer member requires 8-byte alignment, while the subsequent __u16 members only occupy 4 bytes total. The compiler inserts padding between these members for proper alignment, but this padding was not being explicitly zeroed before the structure was copied to user space.

Root Cause

The root cause is the failure to zero-initialize the entire struct iw_point structure before populating it with data and copying it to user space. When structures with padding bytes are allocated on the stack or heap without explicit initialization, the padding bytes retain whatever data was previously present in that memory location. This residual data from previous kernel operations can contain sensitive information such as kernel addresses, cryptographic material, or other privileged data.

Attack Vector

An attacker with local access to the system can exploit this vulnerability by invoking wireless extension ioctl calls that cause the kernel to return an iw_point structure. By examining the returned data, the attacker can extract the uninitialized 32 bits of kernel memory. While the attack vector requires local access and the amount of leaked data is limited, repeated exploitation could allow an attacker to build a picture of kernel memory layout, potentially defeating KASLR (Kernel Address Space Layout Randomization) or gathering other security-sensitive information.

The vulnerability is exploited through the standard wireless extensions interface, making it accessible to any local user with permissions to interact with wireless devices.

Detection Methods for CVE-2026-22978

Indicators of Compromise

• Unusual frequency of wireless extension ioctl calls from user-space applications
• Suspicious processes repeatedly querying wireless interfaces without legitimate networking purposes
• Memory analysis showing extraction patterns targeting the padding bytes of wireless structures

Detection Strategies

• Monitor for excessive SIOCGIWESSID, SIOCGIWENCODE, or similar wireless ioctl system calls from non-standard processes
• Implement audit rules for wireless extension system calls using Linux audit subsystem
• Deploy kernel-level monitoring to detect patterns of information gathering through ioctl interfaces

Monitoring Recommendations

• Enable system call auditing for wireless-related ioctls on systems where WiFi is not actively used
• Review logs for applications making repeated wireless queries without network configuration changes
• Consider using SentinelOne's kernel-level visibility to detect anomalous ioctl patterns

How to Mitigate CVE-2026-22978

Immediate Actions Required

• Update the Linux kernel to a patched version that includes the fix for CVE-2026-22978
• Prioritize patching on systems with sensitive data or multi-user environments
• Review running processes for any suspicious wireless interface queries
• Consider disabling wireless extensions if legacy WiFi functionality is not required

Patch Information

The Linux kernel maintainers have released patches that explicitly zero the struct iw_point structure before use, ensuring no uninitialized memory is leaked to user space. Multiple commits have been merged to stable kernel branches:

• Kernel Git Commit 024f71a
• Kernel Git Commit 21cbf88
• Kernel Git Commit 442cea
• Kernel Git Commit a3827e
• Kernel Git Commit d21ec8
• Kernel Git Commit d943b5
• Kernel Git Commit e3c351

Workarounds

• Disable wireless extensions (WEXT) if using modern cfg80211/nl80211 wireless stack exclusively
• Restrict access to wireless devices using udev rules or device permissions
• Implement namespace isolation for containers to limit wireless interface access
• Use mandatory access control (SELinux/AppArmor) policies to restrict ioctl access to wireless devices

# Configuration example - restrict wireless device access
# Add to /etc/udev/rules.d/99-wifi-restrict.rules
KERNEL=="wlan*", GROUP="netdev", MODE="0660"

# Alternatively, blacklist wireless extensions module if not needed
echo "blacklist cfg80211" >> /etc/modprobe.d/blacklist-wifi.conf