CVE Catalog

CVE-2026-81009

Low risk· EPSS 6%
Published: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.17%

6th percentile - higher than 6% of all known CVEs

Summary

In the Linux kernel, io_handle_query_entry() in the io_uring subsystem 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 may zero out nearly 4 GiB, including on the error path. The interface is reachable without a ring via IORING_REGISTER_QUERY.

Risk Assessment

Excessive zeroing of memory (up to ~4 GiB) can be triggered, potentially leading to denial of service or system destabilization. The vulnerability is locally reachable without special privileges.

Recommendation

Update the Linux kernel to a version that rejects sizes larger than PAGE_SIZE in copy_struct_* interfaces. Consider restricting access to IORING_REGISTER_QUERY for unprivileged users.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS