CVE-2026-43006 io_uring/rsrc: reject zero-length fixed buffer import
A local attacker can trigger an out-of-bounds read in the Linux kernel's io_uring subsystem, potentially leaking memory or causing a crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43006?
CVE-2026-43006 is a high-severity memory corruption vulnerability in Linux kernel, published on 1 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
io_uring/rsrc: reject zero-length fixed buffer import
validate_fixed_range() admits buf_addr at the exact end of the registered region when len is zero, because the check uses strict greater-than (buf_end > imu->ubuf + imu->len). io_import_fixed() then computes offset == imu->len, which causes the bvec skip logic to advance past the last bio_vec entry and read bv_offset from out-of-bounds slab memory.
Return early from io_import_fixed() when len is zero. A zero-length import has no data to transfer and should not walk the bvec array at all.
BUG: KASAN: slab-out-of-bounds in io_import_reg_buf+0x697/0x7f0 Read of size 4 at addr ffff888002bcc254 by task poc/103 Call Trace: io_import_reg_buf+0x697/0x7f0 io_write_fixed+0xd9/0x250 __io_issue_sqe+0xad/0x710 io_issue_sqe+0x7d/0x1100 io_submit_sqes+0x86a/0x23c0 __do_sys_io_uring_enter+0xa98/0x1590 Allocated by task 103: The buggy address is located 12 bytes to the right of allocated 584-byte region [ffff888002bcc000, ffff888002bcc248)
Weakness: CWE-125
Which versions are affected by CVE-2026-43006?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43006?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-43006 being exploited?
There is no known exploitation of CVE-2026-43006 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43006, DEBIAN-CVE-2026-43006, GHSA-5mwr-6pqp-c5qm, UBUNTU-CVE-2026-43006.