CVE-2026-72382

A flaw was found in ksmbd in the Linux kernel. A remote attacker, by sending a specially crafted security descriptor with an undersized Discretionary Access Control List (DACL) during an SMB2_SET_INFO operation, can trigger an integer underflow. This underflow leads to excessive memory allocations for Access Control Entries (ACEs), potentially causing a Denial of Service (DoS) on the system.

An integer underflow in the ksmbd DACL parser can occur when a remote SMB client supplies a DACL size smaller than the struct smb_acl header. The unsigned subtraction in the ACE count validation can turn the remaining DACL length into a very large value, allowing an attacker controlled num_aces value to bypass the intended guard and drive large temporary ACL state and pointer array allocations. For the CVSS the PR:L is used because triggering SMB2_SET_INFO for security information normally requires an authenticated SMB session and sufficient access to the target object, although practical exposure depends on share and guest access configuration. The issue is network reachable when ksmbd is exposed to untrusted SMB clients. Impact is primarily denial of service through memory pressure or allocation failure on the server. No direct UAF or OOB write primitive is evident from the patch, so confidentiality and integrity are not raised in the base score.

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.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.