A new report out today from cybersecurity company Fortra LLC is warning of a vulnerability in all versions of Windows 10 and 11 that, if triggered, could cause system instability and a denial of service.

Tracked as CVE-202406768, the vulnerability is found in the Common Log File System (CLFS.sys) driver of Windows and is caused by improper validation of specified quantities in input data, a situation where the system fails to correctly check or limit the values entered by a user.

The vulnerability can lead to an unrecoverable inconsistency — a critical error in the system’s operations that cannot be corrected — that then triggers the KeBugCheckEx function in Windows and results in instability, including the strong possibility of the dreaded Blue Screen of Death.

Ricardo Narvaja, principal exploit writer at Fortra, designed a proof of concept to demonstrate the vulnerability. The PoC showed that by crafting specific values within a .BLF file, an unprivileged user can induce a system crash. Along with potential issues such as system instability and denial of service, he noted, malicious users could exploit this vulnerability to repeatedly crash affected systems, disrupting operations and potentially causing data loss.

“In the last two research endeavors on Common Log File System (CLFS), I was able to achieve remote code execution in both cases,” Naarvaja wrote. “However, when I modified some values in the PoC I was working on, I observed that it triggered a BSoD on the target system.”

Narvaja adds that the vulnerability is produced by an Improper Validation of Specified Quantity in Input (CWE-1284), which causes an unrecoverable inconsistency in the CLFS.sys driver, forcing a call to the KeBugCheckEx function, which allows an unprivileged user to produce a BSoD in Windows.

Though the vulnerability has been given a Common Vulnerabilities and Exposures score of only 6.8 -Medium, the potential is still there that hackers and other malicious actors could target it and cause disruption in the process.

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