CVE-2026-64324

A flaw was found in the Linux kernel's Universal Disk Format (UDF) filesystem. The udf_free_blocks() function fails to properly validate free block extents against the partition length. This allows a local, unprivileged user to create a specially crafted UDF filesystem that, when a file on it is truncated, can lead to an out-of-bounds read and trigger a kernel panic. This vulnerability results in a Denial of Service (DoS) for the affected system.

This issue is triggered by a specially crafted disk image containing on-disk metadata inconsistencies. Exploitation requires that an attacker convince a user to download and use a malicious image from an untrusted source, a scenario with limited practical impact. Red Hat rates this as Low severity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To prevent the udf kernel module from loading, create a modprobe configuration file.

1. Create /etc/modprobe.d/disable-udf.conf with:

   install udf /bin/true
   blacklist udf
   

2. Regenerate the initramfs:

   dracut -f -v
   

3. Reboot the system. This action will disable UDF filesystem support, potentially affecting systems that rely on UDF media.