CVE-2025-23267: NVIDIA Container Toolkit DoS Vulnerability

CVE-2025-23267 Overview

CVE-2025-23267 is a symlink attack vulnerability (CWE-59) in the NVIDIA Container Toolkit affecting all platforms. The vulnerability exists in the update-ldcache hook, where an attacker could exploit improper link following behavior using a specially crafted container image. A successful exploit of this vulnerability might lead to data tampering and denial of service.

Critical Impact

Attackers can leverage malicious container images to cause the NVIDIA Container Toolkit to follow symlinks improperly, potentially allowing unauthorized modification of files outside the container context and causing service disruption.

Affected Products

• NVIDIA Container Toolkit (all platforms)
• Container environments utilizing NVIDIA GPU support
• Systems running containers with NVIDIA runtime hooks

Discovery Timeline

• 2025-07-17 - CVE-2025-23267 published to NVD
• 2025-11-04 - Last updated in NVD database

Technical Details for CVE-2025-23267

Vulnerability Analysis

This vulnerability is classified as Improper Link Following (CWE-59), a file system vulnerability that occurs when software does not properly handle symbolic links. The update-ldcache hook in the NVIDIA Container Toolkit fails to adequately validate or restrict symlink resolution when processing container images.

When a container is started with NVIDIA GPU support, the toolkit executes various hooks to configure the container environment, including updating the dynamic linker cache. The update-ldcache hook is responsible for configuring library paths within containers to enable GPU acceleration. During this process, the hook follows file paths without properly verifying whether they are symbolic links pointing to locations outside the expected container filesystem.

An attacker can craft a malicious container image containing strategically placed symbolic links that, when processed by the vulnerable hook, cause the toolkit to write or modify files in unintended locations on the host system. This can result in data tampering (modifying critical system files or configuration) and denial of service (corrupting essential components or exhausting system resources).

Root Cause

The root cause stems from insufficient validation in the update-ldcache hook's file handling logic. When the hook traverses directories and processes library files within a container image, it does not implement proper safeguards to prevent symlink following attacks. Specifically, the code fails to:

1. Verify that file paths remain within the container's filesystem boundaries
2. Detect and reject symbolic links pointing to sensitive host locations
3. Use secure file operation primitives that prevent TOCTOU (Time-of-Check Time-of-Use) race conditions

This allows specially crafted container images to include symlinks that redirect file operations to arbitrary locations accessible by the container runtime.

Attack Vector

The attack is network-accessible and requires low privileges, as an attacker needs the ability to run a container using the NVIDIA Container Toolkit. The attack flow typically involves:

1. Malicious Image Preparation: The attacker creates a container image with symbolic links in directories processed by the update-ldcache hook, pointing to sensitive host filesystem locations
2. Container Execution: When a victim runs the malicious container with NVIDIA GPU support enabled, the container runtime invokes the vulnerable hook
3. Symlink Following: The update-ldcache hook follows the embedded symlinks, performing file operations outside the intended container scope
4. Impact Realization: Depending on the symlink targets and operations performed, this results in data tampering or denial of service on the host system

The vulnerability can potentially affect other containers on the same host when exploited, extending the impact beyond the scope of the malicious container itself.

Detection Methods for CVE-2025-23267

Indicators of Compromise

• Unexpected symbolic links within container images targeting host system paths
• Anomalous file modifications in system directories during container startup
• update-ldcache hook activity targeting paths outside container filesystems
• Container images with suspicious symlink structures in library directories

Detection Strategies

• Monitor container runtime hook execution for file operations outside expected paths
• Implement container image scanning to detect suspicious symlink patterns before deployment
• Enable audit logging for file system operations performed by container runtimes
• Deploy SentinelOne Singularity for container environments to detect anomalous file access patterns

Monitoring Recommendations

• Audit update-ldcache hook activity and log all file paths accessed during execution
• Implement real-time monitoring of symbolic link creation and resolution in container environments
• Configure alerts for file modifications in protected system directories during container operations
• Review container image provenance and scan for malicious symlink structures before deployment

How to Mitigate CVE-2025-23267

Immediate Actions Required

• Update NVIDIA Container Toolkit to the latest patched version as specified in the vendor advisory
• Review and validate container images before deployment, particularly checking for suspicious symlinks
• Restrict container execution privileges where NVIDIA GPU support is not required
• Implement container image allowlisting to prevent execution of untrusted images

Patch Information

NVIDIA has released a security update addressing this vulnerability. Organizations should consult the NVIDIA Customer Support Answer for detailed patch information and affected version specifics. Additional technical context is available in the Open Wall OSS Security Post.

Workarounds

• Disable or restrict the update-ldcache hook if GPU cache updates are not required
• Implement container security policies that reject images with symlinks pointing outside container boundaries
• Run containers with read-only root filesystems where possible to limit attack surface
• Use container runtimes with enhanced symlink protection capabilities until patches are applied

# Example: Verify NVIDIA Container Toolkit version
nvidia-container-cli --version

# Example: Check for symlinks in container image layers
find /var/lib/docker/overlay2/<container-layer>/diff -type l -exec ls -la {} \;

# Example: Enable audit logging for container file operations
auditctl -w /var/lib/nvidia-container-toolkit -p rwxa -k nvidia-container-audit