CVE-2025-38111: net/mdiobus: Fix potential out-of-bounds read/write access

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-03 · updated 2026-10-15
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: net/mdiobus: Fix potential out-of-bounds read/write access When using publicly available tools like 'mdio-tools' to read/write data from/to network interface and its PHY via mdiobus, there is no verification of parameters passed to the ioctl and it accepts any mdio address. Currently there is support for 32 addresses in kernel via PHY_MAX_ADDR define, but it is possible to pass higher value than that via ioctl. While read/write operation should generally fail in this case, mdiobus provides stats array, where wrong address may allow out-of-bounds read/write. Fix that by adding address verification before read/write operation. While this excludes this access from any statistics, it improves security of read/write operation.

Affected products

Debian Linux: 11.0
Linux kernel: from 5.6 before 5.10.239; from 5.11 before 5.15.186; from 5.16 before 6.1.142; from 6.2 before 6.6.94; from 6.7 before 6.12.34; from 6.13 before 6.15.3 — fixed in 5.10.239, 5.15.186, 6.1.142, 6.12.34, 6.15.3, 6.6.94

How to fix

Upgrade to a fixed version: Linux kernel 5.10.239, 5.15.186, 6.1.142, 6.12.34. Check the vendor advisory for mitigations.

References

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