Buffer Overflow Risk in Linux Kernel Due to DACL Size Mismanagement

CVE-2026-31704

What is CVE-2026-31704?

A vulnerability in the Linux kernel's ksmbd component involves the incorrect handling of DACL size accumulation. Specifically, the functions set_posix_acl_entries_dacl() and set_ntacl_dacl() utilize u16 variables to keep track of ACE sizes. This can result in an overflow when many POSIX ACL entries are present, leading to potential overlaps in memory where earlier entries may be unintentionally overwritten. To mitigate this risk, the implementation now incorporates check_add_overflow() to monitor size accumulation, preventing the risk of buffer corruption and maintaining the integrity of ACL entries.

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