CVE-2026-64324
Description
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.
Statement
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.
Mitigation
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/true2. Regenerate the initramfs:
blacklist udf
bash3. Reboot the system.
dracut -f -v
This action will disable UDF filesystem support, potentially affecting systems that rely on UDF media.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.7 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | Required | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
Frequently Asked Questions
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