CVE-2026-64294: In the Linux kernel, the following vulnerability has been resolved: mm: do file ownership checks with the proper mount
Summary
A vulnerability in the Linux kernel's memory management code was found where ownership checks in mincore() and madvise() functions were using the wrong idmap (identity map, a translation layer that determines which user owns a file in different mount contexts). This caused permission checks to fail incorrectly for files on idmapped mounts (mounted filesystems with user ID translations), allowing or blocking access when it shouldn't. The fix introduces a new function called file_owner_or_capable() that performs ownership checks using the correct idmap.
Solution / Mitigation
The kernel introduced a new function called file_owner_or_capable() to properly handle ownership checks with the correct idmap semantics, and switched the various users in the memory management code to use this new function instead of the previous incorrect approach.
Vulnerability Details
EPSS: 0.0%
July 25, 2026
Classification
Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-64294
First tracked: July 25, 2026 at 08:10 AM
Classified by LLM (prompt v3) · confidence: 95%