CVE-2026-63298 in LXD
Summary
by MITRE • 08/12/2026
An improper neutralization of special elements vulnerability in LXD's NVIDIA instance configuration handling allows an authenticated attacker to inject arbitrary configuration directives. By supplying newline characters within the 'nvidia.driver.capabilities' or 'nvidia.require.*' configuration values, an attacker can manipulate the generated lxc.conf file. This flaw enables the attacker to execute arbitrary code on the host system with the privileges of the LXD daemon.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical improper neutralization of special elements flaw that affects LXD's handling of NVIDIA instance configurations. The issue manifests when the system processes configuration values for 'nvidia.driver.capabilities' or 'nvidia.require.*' parameters, where attacker-controlled input containing newline characters can be exploited to inject arbitrary configuration directives into the generated lxc.conf file. This type of vulnerability falls under CWE-174, specifically addressing the improper neutralization of special elements that could lead to code injection attacks. The flaw exists at the input validation and configuration generation layer, where proper sanitization of user-provided values fails to account for control characters that can alter the structure of generated configuration files.
The operational impact of this vulnerability is severe as it allows authenticated attackers with access to LXD instance configuration capabilities to escalate privileges and execute arbitrary code on the host system with the same privileges as the LXD daemon. The attack vector relies on the manipulation of configuration value inputs through newline character injection, which can cause the lxc.conf file generation process to interpret additional configuration directives beyond what was intended. This creates a path for privilege escalation from the authenticated user context to the root-level privileges of the host system, effectively compromising the entire infrastructure that LXD manages.
The technical exploitation requires an authenticated user with permission to configure LXD instances, making this vulnerability particularly dangerous in environments where multiple users have access to instance configuration capabilities. The attack chain involves crafting malicious input values containing newline characters that when processed by LXD's NVIDIA configuration handler, result in the injection of additional directives into the lxc.conf file. These injected directives can include commands such as 'lxc.hook.pre-start' or other host-level configuration options that execute with elevated privileges during container initialization.
This vulnerability directly aligns with ATT&CK technique T1059.001 for command and script injection, and T1548.001 for abuse of legitimate credentials through privilege escalation. The flaw demonstrates a classic lack of proper input sanitization in configuration handling processes, where the system fails to properly escape or validate control characters that could alter the intended behavior of generated configuration files. Organizations using LXD with NVIDIA GPU support are particularly at risk, as this vulnerability can be exploited without requiring additional privileges beyond authentication access to instance configuration interfaces.
Mitigation strategies should focus on implementing robust input validation and sanitization for all configuration parameters, specifically ensuring that newline characters and other control characters are properly escaped or rejected during configuration value processing. The LXD daemon should enforce strict validation rules that prevent the injection of special characters into configuration values, with automatic sanitization of user inputs before they are processed into lxc.conf files. Additionally, implementing least privilege principles for LXD configuration access and regular security auditing of configuration handling code can help prevent exploitation attempts. System administrators should also consider applying immediate patches from the LXD project that address this specific input validation flaw and ensure that all configuration parameters undergo proper neutralization before being written to system configuration files.