CVE-2026-63298: LXD arbitrary lxc.conf directive injection via NVIDIA instance configuration

Severity: critical (CVSS 9.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-08-12 · updated 2026-10-24
Weakness: CWE-78

Description

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.

Affected products

Canonical LXD: from 4.0.0 before 4.0.12; from 5.0.0 before 5.0.8; from 5.1 before 5.21.6; from 6.0 through 6.9 — fixed in 4.0.12, 5.0.8, 5.21.6

How to fix

Upgrade to a fixed version: Canonical LXD 4.0.12, 5.0.8, 5.21.6. Check the vendor advisory for mitigations.

References

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