In Linux-based operating systems, the Linux kernel is responsible for controlling hardware resources, device drivers, memory, and networking. Device drivers execute with kernel-level privileges, and any vulnerability in them may impact the overall security and stability of the system.
CVE-2025-68256 is a security vulnerability in the Linux kernel RTL8723BS Wi-Fi driver. Improper validation of Wi-Fi Information Elements (IEs) after parsing can lead to an out-of-bounds read or an infinite loop when processing malformed wireless frames, according to the official Linux kernel security advisory.
What is CVE-2025-68256?
CVE-2025-68256 is a memory safety vulnerability found in the RTL8723BS Wi-Fi driver for the Linux kernel. The issue is in the rtw_get_ie() function, which parses IEEE 802.11 Information Elements (IEs) from Wi-Fi management frames.
The official Linux kernel advisory states that the parser does not properly check whether the advertised Information Element length fits within the remaining frame buffer. This can lead to an out-of-bounds read or an infinite loop when parsing malformed frames. The bug has been fixed in later kernel releases.
What is the Linux Kernel RTL8723BS Wi-Fi Driver?
RTL8723BS Wi-Fi Driver is a Linux kernel module that acts as a Wi-Fi driver for devices which make use of the wireless chip based on the chipset RTL8723BS from the manufacturer Realtek. This driver allows communication between Linux kernel and wireless hardware through processing of Wi-Fi packets, making wireless connections and dealing with IEEE 802.11 management frames. This driver is part of the source code of the Linux kernel located at the staging directory and mostly works on specific laptops and IoT systems.
What are Wi-Fi Information Elements (IEs)?
The Wi-Fi Information Elements (IEs) are data items present inside IEEE 802.11 management frames such as beacon, probe request, and probe response frames. Every Information Element consists of an element identifier (ID), the Length of the element, and the actual data itself.
The information elements carry information related to wireless networks such as network name (SSID), available data rates, security features, and so on. The information elements are parsed by the Linux kernel driver for managing wireless communications.
Understanding Out-of-Bounds Read Vulnerabilities (CWE-125)
An Out-of-Bounds Read (CWE-125) vulnerability occurs when a program reads data from a memory location beyond the allocated buffer boundary. This typically happens when the length or size of input data is not validated before a memory access is performed. Out-of-bounds reads can result in exposure of sensitive memory contents, application crashes, or Denial of Service conditions.
How Does CVE-2025-68256 Work?
As stated in the Linux kernel security notice, the vulnerability occurs in the rtw_get_ie() function while parsing Wi-Fi Information Elements. The problem is that the function does not verify whether the Length field in a Wi-Fi Information Element is valid before reading data based on it.
A specially crafted wireless management frame containing a malformed length value can trigger a buffer over-read or cause the parser to enter an infinite loop. The patch that fixes this vulnerability adds proper boundary checks on the length field.
Affected Linux Kernel Versions
According to the official Linux kernel advisory, the vulnerable implementation was introduced after Linux kernel 4.12 and has been corrected in supported stable kernel releases. Fixes are available in Linux 5.15.203, 6.1.160, 6.6.120, 6.12.62, 6.17.12, 6.18.1, and later supported versions. Users should install the latest security updates provided by their Linux distribution to mitigate the vulnerability.
CVSS Score and Severity of CVE-2025-68256
At the time of this publication, no official CVSS v3.x base score has been assigned to CVE-2025-68256 by the National Vulnerability Database (NVD). Security patches have been published by the Linux kernel security team. Administrators should monitor the NVD and the Linux kernel security mailing list for any future severity classification updates.
Impact of CVE-2025-68256
CVE-2025-68256 is an out-of-bounds read vulnerability in the Linux kernel’s RTL8723BS Wi-Fi driver (rtl8723bs). The vulnerability occurs in the rtw_get_ie() function when processing IEEE 802.11 Wi-Fi management frames received over the wireless interface. An attacker within wireless range can send a specially crafted management frame to trigger the flaw.
The primary operational impacts include:
- Denial of Service (System Crash): Processing a malformed wireless frame with an incorrect Information Element length can cause the kernel’s Wi-Fi driver to read beyond the allocated buffer or enter an infinite loop, causing the kernel to become unresponsive or crash.
- Kernel Memory Disclosure: An out-of-bounds read may expose adjacent memory contents to the parser. Depending on what resides in adjacent memory, this could result in unintended disclosure of sensitive kernel memory data.
- Infinite Loop / System Hang: If the malformed length value causes an infinite loop in the frame parsing routine, the affected system may become unresponsive until the Wi-Fi driver is unloaded or the system is rebooted.
How to Detect CVE-2025-68256
- Check Linux Kernel Version: Run uname -r to determine the installed kernel version. Verify whether your distribution’s kernel includes the upstream patch for the rtl8723bs Wi-Fi driver addressing CVE-2025-68256. Fixed versions include Linux 5.15.203, 6.1.160, 6.6.120, 6.12.62, 6.17.12, 6.18.1, and later.
- Verify Active Driver Modules: Check if the affected Realtek RTL8723BS Wi-Fi driver module is loaded into the running kernel:
Bash
lsmod | grep rtl8723bs
- Inspect System Logs (dmesg / syslog): Monitor system logs for kernel warnings, memory boundary violations, or driver crashes originating from the rtl8723bs driver or the rtw_get_ie() parsing routine:
Bash
dmesg | grep -i rtl8723bs
How to Fix CVE-2025-68256
Update the Linux Kernel: Apply the official Linux kernel update provided by your distribution vendor (e.g., Ubuntu, Debian, RHEL, Arch) that incorporates the upstream bounds checking fix for the rtl8723bs Wi-Fi driver.
Reboot the Operating System: Restart the host system to unload the vulnerable kernel image and ensure the newly patched driver is loaded into memory.
Blacklist the Vulnerable Module (Workaround): If an immediate kernel update is not feasible and the RTL8723BS Wi-Fi hardware is not essential to system operations, temporarily blacklist the rtl8723bs driver module:
Bash
echo “blacklist rtl8723bs” >> /etc/modprobe.d/blacklist-rtl8723bs.conf
Best Practices to Prevent Wi-Fi Driver Memory Safety Vulnerabilities
- Strict Input & Frame Length Validation: Ensure low-level wireless network drivers enforce strict bounds checking on variable-length information elements (IEs) before copying payload data into allocated memory buffers.
- Enable Kernel Hardening Features: Keep kernel protection mechanisms enabled, such as Kernel Address Space Layout Randomization (KASLR), Control Flow Integrity (CFI), and compiler-level stack protection (CONFIG_STACKPROTECTOR).
- Unload Unused Wireless Drivers: Automatically disable or blacklist driver modules for hardware interfaces that are not actively in use on servers or enterprise workstations.
- Implement Automated Security Patching: Establish routine patch management pipelines to deliver kernel updates as upstream security patches become available.
Frequently Asked Questions (FAQs)
Conclusion
CVE-2025-68256 illustrates how missing boundary checks in Wi-Fi frame parsing routines can lead to out-of-bounds reads and system instability. Because the RTL8723BS driver is present in many embedded Linux and IoT devices, applying kernel updates that include the upstream fix is important. Timely kernel maintenance, blacklisting unused wireless drivers, and enabling kernel hardening features provide a strong and layered defence across enterprise and embedded deployments.
