CVE-2025-20654 - Out of Bounds Write in WLAN service leads to Remote Code Execution

Introduction:

In the world of cybersecurity, vulnerabilities are constantly being discovered and exploited by attackers. The Common Vulnerabilities and Exposures (CVE) system both identifies and categorizes these threats, making it easier for developers to identify and fix potential safety issues. Today, we turn our attention to a critical vulnerability recently identified within the WLAN service: CVE-2025-20654.

Summary

CVE-2025-20654 details a possible out of bounds write due to an incorrect bounds check in the WLAN service. This vulnerability can lead to remote code execution without any additional execution privileges required. Furthermore, user interaction is not necessary for exploitation. The issue has been identified with Patch ID WCNCR00406897 and Issue ID MSV-2875.

Background

WLAN (Wireless Local Area Network) services provide wireless connectivity to devices within a local area. These services are crucial for secure and reliable communication on various platforms. In this case, the vulnerability occurs when an attacker manages to exploit an out of bounds write error due to an incorrect bounds check.

An out of bounds write occurs when a program writes data to a buffer but ends up writing outside the buffer's boundary. As a result, the adjacent memory gets overwritten, which can lead to unexpected behavior, crashes, or even remote code execution. In the case of CVE-2025-20654, this can be accomplished without any additional execution privileges needed.

The following code snippet demonstrates the out of bounds write vulnerability in wlan_service

// vulnerable function in wlan_service.c
int wlan_service_process_packet(char *packet, int length) {
    char buf[256];
    if (length > sizeof(buf)) { // incorrect bounds check
        return -1;
    }
    memcpy(buf, packet, length); // out of bounds write
    ...
}

In the above code snippet, the wlan_service_process_packet function processes a given packet and copies the packet data to a local buffer (buf) using memcpy. The function first checks if the packet length is greater than the buffer size. However, this check is incorrect because it does not account for the fact that the packet's length might be negative.

An attacker could exploit this vulnerability by sending a packet with a negative length and cause an out of bounds write. Since user interaction is not required, the attacker could remotely exploit this vulnerability by merely sending a specially crafted packet to the victim's WLAN service.

Mitigation and Patch

The issue has been addressed and resolved with Patch ID WCNCR00406897 and Issue ID MSV-2875. To mitigate this vulnerability, users are encouraged to apply the patch as soon as possible. Below is the patched code, which correctly handles the bounds check:

// fixed function in wlan_service.c
int wlan_service_process_packet(char *packet, int length) {
    char buf[256];
    if (length <  || length > sizeof(buf)) { // correct bounds check
        return -1;
    }
    memcpy(buf, packet, length); // safe operation
    ...
}

The patch adds an explicit check for negative values, ensuring that the memcpy operation is safe and does not result in an out of bounds write.

For more information about the vulnerability, you can consult the following sources

1. CVE-2025-20654 - Official CVE Details
2. WCNCR00406897 - Patch Details
3. MSV-2875 - Issue Details

Conclusion

CVE-2025-20654 poses a significant risk of remote code execution by exploiting an out of bounds write vulnerability in the WLAN service. It is crucial for users to update their systems with the provided patch and stay vigilant to protect against attacks that aim to exploit such vulnerabilities.

Timeline

Published on: 04/07/2025 04:15:19 UTC
Last modified on: 04/09/2025 15:46:21 UTC