CVE-2026-64120 net: ethtool: fix NULL pointer dereference in phy_reply_size
A missing NULL check in the Linux kernel's ethtool subsystem can cause a kernel panic, leading to a denial of service.
- 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-2026-64120?
CVE-2026-64120 is a medium-severity vulnerability in Linux kernel, published on 19 Jul 2026. 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: ethtool: fix NULL pointer dereference in phy_reply_size
In phy_prepare_data(), several strings such as 'name', 'drvname', 'upstream_sfp_name', and 'downstream_sfp_name' are allocated using kstrdup(). However, these allocations were not checked for failure.
If kstrdup() fails for 'name', it returns NULL while the function continues. This leads to a kernel NULL pointer dereference and panic later in phy_reply_size() when it unconditionally calls strlen() on the NULL pointer.
While other strings like 'upstream_sfp_name' might be checked before access in certain code paths, failing to handle these allocations consistently can lead to incomplete data reporting or hidden bugs.
Fix this by adding proper NULL checks for all kstrdup() calls in phy_prepare_data() and implement a centralized error handling path using goto labels to ensure all previously allocated resources are freed on failure.
Weakness: CWE-476
Which versions are affected by CVE-2026-64120?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64120?
Apply the vendor's patch.
Is CVE-2026-64120 being exploited?
There is no known exploitation of CVE-2026-64120 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64120, DEBIAN-CVE-2026-64120, GHSA-4j8v-vv2j-8xpv, UBUNTU-CVE-2026-64120.