Out-of-Bounds Vulnerability in Linux Kernel Affecting SMB Protocol

CVE-2025-40099

What is CVE-2025-40099?

A vulnerability exists in the Linux kernel's handling of SMB protocol communications, specifically in the CIFS module. An attacker can exploit this flaw by sending malformed responses from a malicious SMB server, which may lead to out-of-bounds access. This occurs when the server's reply is either smaller than the expected size of the designated response structure or contains a number of referrals that does not match the expected value, potentially leading to memory corruption. The kernel has implemented safeguards to return an -EINVAL error to mitigate these out-of-bounds issues.

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