CVE intelligence

CVE-2026-81009

Vulnerability intelligence

Published Sep 11, 2026Sources checked Nov 3, 2026

N/ACVSS not listedScore unavailable

What this means

Review the available evidence

CVE-2026-81009. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.2%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-81009?

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.

Source: NVD