Privilege Escalation in NVIDIA Linux CUDA Driver via Improper IOCTL Handling
Overview
NVIDIA released a security bulletin addressing a high-severity privilege escalation vulnerability in its Linux GPU driver. The vulnerability, identified as CVE-2026-28215, resides in the CUDA driver's IOCTL (Input/Output Control) handler responsible for managing GPU memory. A flaw in the validation logic for memory-mapped I/O (MMIO) operations allows a local, low-privileged user to craft a specific IOCTL request that causes the driver to write data to an arbitrary physical memory address. By carefully selecting the target address, an attacker can overwrite critical kernel data structures, function pointers in kernel space, or page table entries. Successful exploitation of this vulnerability allows the local attacker to execute arbitrary code with kernel-level privileges, resulting in a full loss of confidentiality, integrity, and availability. This is particularly dangerous in multi-tenant environments such as university clusters, cloud-based Jupyter notebook services, or shared ML training platforms, where multiple users with restricted shell access share the same physical GPUs. A malicious user on such a platform could exploit this flaw to escape their container or user session and gain complete root control over the host machine, compromising all other users' data and workloads.
Affected Systems
Testing Guide
1. **Check Driver Version**: Run the command `nvidia-smi` on the Linux host. The driver version is displayed in the top right corner. 2. **Compare with Patched Version**: If the displayed version is less than `555.58.02`, your system is vulnerable. 3. **Consult Security Bulletin**: Cross-reference your driver branch (e.g., 550, 535) with the official NVIDIA Security Bulletin to find the correct patched version for your specific release series.
Mitigation Steps
1. **Update NVIDIA Drivers**: The most effective mitigation is to update the NVIDIA driver to the patched version specified in the security bulletin (555.58.02 or newer). 2. **Restrict GPU Access**: In multi-tenant environments, use security mechanisms like cgroups and AppArmor/SELinux to restrict which users and containers can access GPU device nodes (`/dev/nvidia*`). 3. **Kernel Hardening**: Ensure standard kernel hardening features are enabled, such as Kernel Page-Table Isolation (KPTI) and Control-Flow Enforcement Technology (CET), which can make exploitation more difficult. 4. **Monitor for Malicious Activity**: Monitor GPU usage and system calls for anomalous patterns that could indicate an exploitation attempt.
Patch Details
NVIDIA has released patched driver version 555.58.02 and has backported the fix to multiple production driver branches. Consult the official NVIDIA security bulletin for the appropriate version for your system.