CVE-2026-24708: OpenStack Nova Unsafe Image Resize Vulnerability
Summary
CVE-2026-24708: OpenStack Nova calls qemu-img without format restrictions for resize. Affects nova across 3 version ranges.
< 30.2.1
>= 31.0.0.0rc1, <= 31.2.0
>= 32.0.0.0rc1, <= 32.1.0
No fix is published. How to fix ↓
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Background
OpenStack Nova is a core component of the OpenStack cloud computing platform, responsible for managing compute resources and providing services for virtual machines. It allows users to create, manage, and scale virtual instances in a cloud environment. The package is widely used in cloud infrastructures, making its security critical. This vulnerability arises from the improper handling of image formats during the resizing of virtual disks, which can lead to significant data loss.
Vulnerability Detail
An issue was discovered in OpenStack Nova before versions 30.2.2, 31 before 31.2.1, and 32 before 32.1.1. By crafting a malicious QCOW header for a root or ephemeral disk and triggering a resize operation, a user can exploit Nova's Flat image backend to call qemu-img without format restrictions. This unsafe operation can potentially destroy data on the host system, particularly affecting compute nodes configured with use_cow_images=False.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can avoid using the Flat image backend or ensure that the configuration for use_cow_images is set to True. This can be done by modifying the Nova configuration file (usually located at /etc/nova/nova.conf) and setting the following parameter: use_cow_images=True.
Conclusion
The CVE-2026-24708 vulnerability in OpenStack Nova poses a significant risk to data integrity during image resize operations. Users are strongly advised to upgrade to the latest patched versions to mitigate this risk. Implementing the provided workaround can also help in the interim.
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FAQ
CVE-2026-24708 is a vulnerability in OpenStack Nova that allows for unsafe image resize operations, potentially leading to data loss.
Versions of OpenStack Nova before 30.2.2, 31 before 31.2.1, and 32 before 32.1.1 are affected by this vulnerability.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The CVSS score of this vulnerability is 8.2, indicating a high severity level.
If an immediate upgrade is not possible, consider applying the mentioned workaround by changing the configuration to use cow images.
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