CVE-2026-64120
Received Received - Intake

NULL Pointer Dereference in Linux Kernel ethtool

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

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.

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-64120
EUVD
EUVD-2026-45805

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a NULL pointer dereference vulnerability in the Linux kernel's ethtool subsystem. It occurs when kstrdup() fails to allocate memory for strings like 'name' in the phy_prepare_data() function. Since the failure isn't checked, the function continues with NULL pointers. Later, when phy_reply_size() calls strlen() on these NULL pointers, it causes a kernel panic.

Detection Guidance

This vulnerability is specific to the Linux kernel's ethtool subsystem and requires kernel-level inspection. Detection involves checking kernel logs for NULL pointer dereference errors or kernel panics related to phy_reply_size. Monitor system logs with commands like dmesg | grep -i 'NULL pointer' or journalctl -k | grep -i 'panic'. Ensure your kernel version is updated to a patched release.

Impact Analysis

This vulnerability can cause system crashes (kernel panics) when specific ethtool operations are performed on network interfaces using PHY devices. The crash would result in an immediate system reboot or freeze, leading to downtime and potential data loss.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it is a kernel-level NULL pointer dereference issue in the Linux network subsystem. Compliance impacts would only occur if the vulnerability leads to system crashes or data corruption during network operations, which could indirectly affect data integrity or availability.

Mitigation Strategies

Update your Linux kernel to the latest stable version that includes the fix for CVE-2026-64120. If immediate patching is not possible, restrict access to ethtool operations or disable untrusted user access to network interfaces until the update is applied.

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