CVE-2026-68293
Received Received - Intake

Buffer Overflow in Linux Kernel's mlx5 Driver

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: kernel.org

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.

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
CVE-2026-68293
EUVD
EUVD-2026-55394

Affected Vendors & Products

Currently, no data is known.

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a buffer overflow vulnerability in the Linux kernel's mlx5 driver. It occurs when reading the MCIA register which can return up to 32 dwords (128 bytes) of data, but the buffer is only sized for 12 dwords (48 bytes). This causes a memcpy to read past the buffer end, triggering a buffer overflow detected by FORTIFY_SOURCE when querying module EEPROM via ethtool.

Detection Guidance

This vulnerability is detected by kernel crashes when querying module EEPROM via ethtool on systems with affected Linux kernels. Check kernel logs for buffer overflow errors during ethtool operations.

Impact Analysis

This vulnerability could cause kernel crashes or system instability when querying module EEPROM via ethtool. On systems with FORTIFY_SOURCE enabled, it triggers a buffer overflow panic, potentially leading to denial of service or requiring a system reboot.

Mitigation Strategies

Apply the Linux kernel patch that extends the mcia_reg layout to 32 dwords. Update to a fixed kernel version where this issue is resolved.

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