CVE-2026-72382
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk45th percentile - higher than 45% of all known CVEs
Summary
In the Linux kernel's ksmbd server, a vulnerability was found where undersized DACLs are not properly rejected before parsing ACEs. Due to an underflow in the calculation, a malicious client can bypass the ACE count limit and cause excessive memory allocations.
Risk Assessment
A malicious client could cause memory exhaustion or system crash, threatening service availability.
Recommendation
Install an updated Linux kernel with the fix that rejects DACLs smaller than struct smb_acl before performing the subtraction.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ksmbd: reject undersized DACLs before parsing ACEs parse_dacl() limits the attacker-controlled ACE count by comparing it with the number of minimal ACEs that fit in the DACL size. The DACL size field is 16 bits, but the expression subtracts sizeof(struct smb_acl). Because sizeof() is unsigned, a DACL size smaller than the ACL header underflows to a large size_t. A malicious client can reach this with: SMB2_SET_INFO (InfoType=SMB2_O_INFO_SECURITY) -> smb2_set_info_sec() -> set_info_sec() -> parse_sec_desc() -> parse_dacl() -> init_acl_state(..., 0xffff) -> init_acl_state(..., 0xffff) -> kmalloc_objs(..., 0xffff) Thus a malformed security descriptor can make num_aces pass the guard and drive large temporary ACL state and pointer-array allocations. Reject DACLs smaller than struct smb_acl before doing the subtraction, so the ACE count check cannot be bypassed by the underflow.