CVE-2026-31774

About vulnerability

In the Linux kernel, the following vulnerability has been resolved: io_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs() sqe->len is __u32 but gets stored into sr->len which is int. When userspace passes sqe->len values exceeding INT_MAX (e.g. 0xFFFFFFFF), sr->len overflows to a negative value. This negative value propagates through the bundle recv/send path:

1. io_recv(): sel.val = sr->len (ssize_t gets -1)
2. io_recv_buf_select(): arg.max_len = sel->val (size_t gets 0xFFFFFFFFFFFFFFFF)
3. io_ring_buffers_peek(): buf->len is not clamped because max_len is astronomically large
4. iov[].iov_len = 0xFFFFFFFF flows into io_bundle_nbufs()
5. io_bundle_nbufs(): min_t(int, 0xFFFFFFFF, ret) yields -1, causing ret to increase instead of decrease, creating an infinite loop that reads past the allocated iov[] array This results in a slab-out-of-bounds read in io_bundle_nbufs() from the kmalloc-64 slab, as nbufs increments past the allocated iovec entries. BUG: KASAN: slab-out-of-bounds in io_bundle_nbufs+0x128/0x160 Read of size 8 at addr ffff888100ae05c8 by task exp/145 Call Trace: io_bundle_nbufs+0x128/0x160 io_recv_finish+0x117/0xe20 io_recv+0x2db/0x1160 Fix this by rejecting negative sr->len values early in both io_sendmsg_prep() and io_recvmsg_prep(). Since sqe->len is __u32, any value > INT_MAX indicates overflow and is not a valid length. A flaw was found in the Linux kernel’s io_uring networking component. A local attacker could exploit an integer overflow vulnerability by providing a specially crafted length value. This issue leads to a slab-out-of-bounds read, which could allow for information disclosure or potentially cause a denial of service (DoS) by making the system unresponsive.

Live-patch status from KernelCare for each operating system.