CVE-2026-52937 Linux CVE debrief

Who should care

System administrators and security teams managing Linux kernel-based systems, especially those using macvtap chardev, should be aware of this vulnerability. They should assess their exposure and apply patches or mitigations as necessary to prevent potential information disclosure.

Technical summary

The tap_ioctl() function in the Linux kernel, when handling SIOCGIFHWADDR requests, copies 16 bytes of an uninitialized on-stack struct sockaddr_storage to userspace via ifr_hwaddr. However, netif_get_mac_address() only initializes sa_family and dev->addr_len (6 bytes for Ethernet), leaving the remaining 8 bytes (sa_data[6..13]) uninitialized. These uninitialized bytes can leak kernel stack contents, including potentially sensitive information like kernel .text and direct-map pointers, which could be used to defeat Kernel Address Space Layout Randomization (KASLR). The vulnerability was resolved by initializing the struct sockaddr_storage at declaration.

Defensive priority

Medium

Recommended defensive actions

• Apply the official patch to initialize the struct sockaddr_storage in tap_ioctl().
• Inventory Linux kernel-based systems for exposure, especially those using macvtap chardev.
• Monitor system logs for unusual activity that could indicate exploitation attempts.
• Consider implementing additional security controls, such as using secure boot and ensuring up-to-date kernel versions.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record was published on 2026-06-24T08:16:23.980Z and was last modified on 2026-07-07T18:35:34.340Z. The NVD entry is currently Awaiting Analysis. The vulnerability was resolved by initializing the struct sockaddr_storage at declaration. Three source references are provided, pointing to the Linux kernel stable repository.

Official resources