CVE-2026-68293 net/mlx5: Fix MCIA register buffer overflow on 32 dword reads
A buffer overflow in the Linux kernel mlx5 driver allows local attackers to cause a system crash via ethtool EEPROM reads.
- 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-2026-68293?
CVE-2026-68293 is a high-severity memory corruption vulnerability in Linux, published on 10 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:
net/mlx5: Fix MCIA register buffer overflow on 32 dword reads
The MCIA register can return up to 32 dwords (128 bytes) when the device advertises the mcia_32dwords capability, but struct mlx5_ifc_mcia_reg_bits only defines dword_0..11, leaving room for just 12 dwords (48 bytes) of data.
mlx5_query_mcia() clamps the read size to mlx5_mcia_max_bytes() and then memcpy()s that many bytes out of the register, potentially reading past the end of the 'out' buffer. On kernels built with FORTIFY_SOURCE this is caught as a buffer overflow while reading the module EEPROM via ethtool:
detected buffer overflow in memcpy kernel BUG at lib/string_helpers.c:1048! RIP: 0010:fortify_panic+0x13/0x20 Call Trace: mlx5_query_mcia.isra.0+0x200/0x210 [mlx5_core] mlx5_query_module_eeprom_by_page+0x4a/0xa0 [mlx5_core] mlx5e_get_module_eeprom_by_page+0xbb/0x120 [mlx5_core] eeprom_prepare_data+0xf3/0x170 ethnl_default_doit+0xf1/0x3b0
Extend the mcia_reg layout to 32 dwords.
Weakness: CWE-122
Which versions are affected by CVE-2026-68293?
How do I fix CVE-2026-68293?
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-2026-68293 being exploited?
There is no known exploitation of CVE-2026-68293 in the wild and no public exploit code.
Sources
Also known as AZL-95087, BELL-CVE-2026-68293, DEBIAN-CVE-2026-68293, GHSA-7555-mcj4-25r2, UBUNTU-CVE-2026-68293.