In June 2025, a new Windows vulnerability was uncovered and assigned CVE-2025-55695. This bug affects the Windows WLAN Auto Config Service (also known as wlansvc), allowing an attacker with regular user privileges to read sensitive information from memory. If exploited, it could expose details such as credentials, system tokens, or private data within the affected memory space.

In this post, we break down the vulnerability, show a code sample that demonstrates the risk, and reference further sources for in-depth research.

What is Windows WLAN Auto Config Service?

The Windows WLAN Auto Config Service (wlansvc) is responsible for managing wireless network connections and their profiles on a Windows system. It's always running on most laptops, desktops, and tablets, especially on systems frequently connecting to Wi-Fi networks.

Due to its central role, bugs in this service can have broad impact on privacy and security.

Vulnerability Details

CVE-2025-55695 is an out-of-bounds (OOB) read bug. This happens when a program reads more data from memory than it's supposed to, often past the end of an array or buffer.

Attack Scenario

An attacker with access to a regular user account can perform certain local operations (such as crafting special WLAN profile requests or malformed SSIDs) that cause the service to read from memory areas outside the normal buffer limits. These areas might contain sensitive data belonging to the service or even other processes.

On exploitation, the service could expose chunks of memory via error logs, user feedback, or even by sending this data over the network if requested in certain conditions.

How Does the Exploit Work?

Let’s examine a simplified example. When a Windows user adds a new Wi-Fi profile, the system parses the profile data. If this data isn’t properly sanity-checked, passing a maliciously crafted input can force the service to read “too much” memory.

For instance, suppose the following C-like pseudocode is responsible for parsing received SSIDs (network names):

void ParseSSID(char *input, int length) {
    char ssidBuffer[32];
    memcpy(ssidBuffer, input, length);   // vulnerability here!
    // ... rest of the code
}

If length (user-supplied) is bigger than 32, data beyond ssidBuffer is read into memory, which constitutes an out-of-bounds read.

A real-world proof-of-concept would use Windows scripting or PowerShell to push a malformed profile or interact with the API:

$ssid = ("A" * 64)  # Oversized SSID
netsh wlan add profile filename="malicious_profile.xml"
# malicious_profile.xml contains the 64-byte SSID

When processed, the oversized SSID triggers the out-of-bounds read, potentially causing the service to expose unintended memory contents in error logs or returns.

Internal configuration details

The leak potential depends on memory usage at the moment of exploitation and how the information is accessed afterward.

Who is at Risk?

This vulnerability only allows *local* exploitation; remote attackers cannot trigger it over the network. However, in environments with many users (schools, multi-user workstations, or shared laptops), local attackers can leverage this to steal information and escalate attacks.

References and Further Reading

- Microsoft Security Advisory for CVE-2025-55695 (archived)
- CVE-2025-55695 at MITRE
- What is Out-of-Bounds Read? (OWASP)

Mitigations

Patches: Microsoft issued a fix in June 2025. Update your Windows devices as soon as possible.

Monitor error and event logs for suspicious entries.

General Advice: Never grant unnecessary local access to shared systems and always apply official security updates.

Conclusion

CVE-2025-55695 is a classic example of a memory handling bug with real-world privacy implications. If you’re a system administrator, ensure your devices are patched. If you’re a developer, use safe memory operations and restrict user input lengths.

Timeline

Published on: 10/14/2025 17:15:51 UTC
Last modified on: 12/11/2025 19:36:00 UTC