CVE-2026-81009

Summary

In the Linux kernel, the following vulnerability has been resolved:

io_uring/query: cap user size passed to copy_struct_to_user

io_handle_query_entry() clamps hdr.size for the inbound copy_from_user() but keeps the original user value as usize. copy_struct_to_user() uses that usize and, when it is larger than the kernel result, clear_user()s the trailing bytes.

As hdr.size is a __u32, a query can request nearly 4 GiB of zeroing, including on the error path where res_size stays 0. The interface is reachable without a ring via IORING_REGISTER_QUERY.

Reject sizes larger than PAGE_SIZE, as recommended for copy_struct_* interfaces.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxc265ae75f900cea4e415230a77b5d152377627dd < 417e02f7b6051765b91cf1289071882eebd172e0affected
LinuxLinuxc265ae75f900cea4e415230a77b5d152377627dd < 2b8ad4981ecedb14c1fdd811ab977010b23933e6affected
LinuxLinuxc265ae75f900cea4e415230a77b5d152377627dd < ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95baffected
LinuxLinux6.18affected
LinuxLinux0 < 6.18unaffected
LinuxLinux6.18.50 <= 6.18.*unaffected
LinuxLinux7.2.4 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References