CVE-2025-21994

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix incorrect validation for num_aces field of smb_acl

parse_dcal() validate num_aces to allocate posix_ace_state_array.

if (num_aces > ULONG_MAX / sizeof(struct smb_ace *))

It is an incorrect validation that we can create an array of size ULONG_MAX. smb_acl has ->size field to calculate actual number of aces in request buffer size. Use this to check invalid num_aces.

This vulnerability is evaluated as having Moderate impact because, while an invalid access control list count in the SMB server can cause memory allocation errors leading to a denial of service, exploiting it requires establishing an authenticated SMB session. Red Hat Enterprise Linux is not affected by this vulnerability as the in-kernel SMB server (ksmbd) is not enabled or distributed in Red Hat kernels.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.