CVE-2025-38086 net: ch9200: fix uninitialised access during mii_nway_restart
A local attacker can read uninitialized kernel memory via the ch9200 network driver due to missing error checks, potentially exposing sensitive data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38086?
CVE-2025-38086 is a medium-severity vulnerability in Debian Debian Linux, published on 28 Jun 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-908
Which versions are affected by CVE-2025-38086?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38086?
Apply the vendor's patch.
Is CVE-2025-38086 being exploited?
There is no known exploitation of CVE-2025-38086 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-64383, BELL-CVE-2025-38086, DEBIAN-CVE-2025-38086, GHSA-33v2-gr7f-4wmr, ROOT-OS-DEBIAN-11-CVE-2025-38086, ROOT-OS-DEBIAN-12-CVE-2025-38086 and 3 more.