CVE-2026-74712 vdpa/mlx5: Fix buffer length in create_direct_keys()
A buffer overflow in the Linux kernel's mlx5 vdpa driver allows out-of-bounds reads, potentially leading to system crashes or code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74712?
CVE-2026-74712 is a critical memory corruption vulnerability in Linux, published on 22 Aug 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:
vdpa/mlx5: Fix buffer length in create_direct_keys()
We have seen in our CI the following KASAN message: BUG: KASAN: slab-out-of-bounds in cmd_exec+0x550/0xca0 [mlx5_core] Read of size 272 at addr 0000000176795020 by task qemu-system-s39/82764 [...] [<000011388ab3a7a0>] cmd_exec+0x550/0xca0 [mlx5_core] [<000011388ab3b61c>] mlx5_cmd_exec_cb+0x25c/0x4f0 [mlx5_core] [<000011388b21e82e>] mlx5_vdpa_exec_async_cmds+0x22e/0x5e0 [mlx5_vdpa] [<000011388b21fd44>] create_direct_keys+0x954/0xef0 [mlx5_vdpa] [...] The buggy address is located 4128 bytes inside of allocated 4384-byte region [0000000176794000, 0000000176795120)
So in essence we read 16 bytes beyond 4384-byte allocation. create_direct_keys calculates the pointer and length for in and out buffers. The size calculation for in includes the entire structure size (out + in + mtt[]) but the pointer passed to cmd_exec points only to the 'in' field, skipping the 'out' field.
This causes mlx5_copy_to_msg() to read beyond the allocated buffer by sizeof(out) bytes when copying command data.
Properly calculate the input size to match the pointer and allocation size.
Which versions are affected by CVE-2026-74712?
How do I fix CVE-2026-74712?
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-2026-74712 being exploited?
There is no known exploitation of CVE-2026-74712 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74712, DEBIAN-CVE-2026-74712, GHSA-8f7v-7fr8-r5c3, UBUNTU-CVE-2026-74712.