CVE-2025-38086: Debian Linux

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: net: ch9200: fix uninitialised access during mii_nway_restart In mii_nway_restart() the code attempts to call mii->mdio_read which is ch9200_mdio_read(). ch9200_mdio_read() utilises a local buffer called "buff", which is initialised with control_read(). However "buff" is conditionally initialised inside control_read(): if (err == size) { memcpy(data, buf, size); } If the condition of "err == size" is not met, then "buff" remains uninitialised. Once this happens the uninitialised "buff" is accessed and returned during ch9200_mdio_read(): return (buff[0] | buff[1] << 8); The problem stems from the fact that ch9200_mdio_read() ignores the return value of control_read(), leading to uinit-access of "buff". To fix this we should check the return value of control_read() and return early on error.

Affected products

• Debian Debian Linux: version 11.0 only
• Linux Linux Kernel: from 4.3.1, before 5.4.295 (fixed in 5.4.295); from 5.5, before 5.10.239 (fixed in 5.10.239); from 5.11, before 5.15.186 (fixed in 5.15.186); from 5.16, before 6.1.142 (fixed in 6.1.142); from 6.2, before 6.6.95 (fixed in 6.6.95); from 6.7, before 6.12.35 (fixed in 6.12.35); …

Published 2025-06-28. Last modified 2026-06-17.