CVE-2025-20654 - Out-of-Bounds Write in WLAN Service May Lead to Remote Code Execution

In early 2025, a critical vulnerability was uncovered in the WLAN service, officially identified as CVE-2025-20654. The flaw allows for a possible out-of-bounds write due to incorrect bounds checking, paving the way for remote code execution without any need for extra privileges or user interaction. This exclusive article breaks down what CVE-2025-20654 is, how it works, and what you should do about it. We’ll also offer example code and useful references.

The Nitty-Gritty: What’s the Problem?

The wireless LAN (WLAN) service in certain devices fails to properly check the bounds of an array or buffer before writing data to it. In programming, every buffer or array has limits—a start and an end. When data gets written outside these limits, it can overwrite other parts of memory, bringing chaos and opening the door for an attacker to run their own code.

Vulnerability Details

At its core, CVE-2025-20654’s issue is a classic buffer overrun caused by a lack of *proper* length checks. Let’s see a simplified, illustrative example:

Suppose the WLAN service handles incoming network data like this

void handle_packet(char* data, int length) {
    char buffer[256];
    // Missing: length check!
    memcpy(buffer, data, length);
}

If an attacker sends a packet larger than 256 bytes, memcpy will keep copying, spilling over buffer and corrupting other parts of memory. If the attacker plants code in the right place, this can lead to the WLAN service executing that code.

Trigger the buffer overrun: The extra data overwrites adjacent memory.

4. Take control: If the overwritten area includes control structures or function pointers, the attacker’s code can be run the next time these functions are called.

Let's look at a basic demonstration in C, not for misuse, but for understanding

// Attacker's crafted packet (pseudo representation)
unsigned char payload[300];
memset(payload, 'A', 299);
payload[299] = '\';

// On the victim's side:
char buffer[256];
// Danger: copying too much!
memcpy(buffer, payload, 300);    // Overwrites memory past the buffer

In a real attack, the payload would contain malicious code instead of ‘A’s, organized so that the overwritten area redirects execution to it.

Links & References

- Qualcomm Security Bulletin (*See March 2025/April 2025 Bulletins*)
- NIST NVD – CVE-2025-20654 (*Pending public page, check back for updates*)
- Mitre CVE Directory
- Buffer Overflows Explained (OWASP)

Patch ID: WCNCR00406897 fixes this by making sure no more than the buffer’s size is copied

void handle_packet(char* data, int length) {
    char buffer[256];
    int copy_len = (length < 256) ? length : 256;
    memcpy(buffer, data, copy_len);
}

Update your devices ASAP if a patch is available!

- Check your vendor’s security page or look for security updates referencing CVE-2025-20654, WCNCR00406897, or MSV-2875.

Conclusion

CVE-2025-20654 is a high-risk vulnerability in WLAN services that can let attackers take over devices by sending specially crafted wireless packets. No action is needed from the victim, and no privileges are needed by the attacker — making this an urgent issue to patch. Keep an eye on official advisories, and update your device firmware as soon as patches become available.

If you’re a developer: never trust external data sizes! Always validate before you copy.

Stay safe, and keep your software up to date.

*This article is exclusive content based on up-to-date public advisories and plausible technical insight.*

Timeline

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