Use-After-Free Vulnerability in Linux Kernel's ext4 Directory Handling

CVE-2026-89787

What is CVE-2026-89787?

A vulnerability in the Linux kernel's ext4 file system could allow an attacker to exploit directory entries through crafted data that bypasses safety checks. Specifically, this issue arises in the handling of casefolded encrypted directories. When an entry's name extends to the end of a block, the current checks fail to account for hash trailers, potentially leading to out-of-bounds reads. This flaw can trigger a use-after-free condition if the memory region following the directory block is accessed improperly. Developers are advised to implement checks to ensure that all components of directory entries, including their trailers, fit within their allocated space before processing them.

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