LXD 4.126.7 PrivEsc: Missing denylist for raw.apparmor & raw.qemu.conf in isVMLowLevelOptionForbidde
CVE-2026-34177 Published on April 9, 2026
VM lowlevel restriction bypass via raw.apparmor and raw.qemu.conf
Canonical LXD versions 4.12 through 6.7 contain an incomplete denylist in isVMLowLevelOptionForbidden (lxd/project/limits/permissions.go), which omits raw.apparmor and raw.qemu.conf from the set of keys blocked under the restricted.virtual-machines.lowlevel=block project restriction. A remote attacker with can_edit permission on a VM instance in a restricted project can inject an AppArmor rule and a QEMU chardev configuration that bridges the LXD Unix socket into the guest VM, enabling privilege escalation to LXD cluster administrator and subsequently to host root.
Vulnerability Analysis
CVE-2026-34177 can be exploited with network access, and requires user privileges. This vulnerability is considered to have a low attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2026-34177. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
Weakness Type
What is a Denylist / Deny List Vulnerability?
The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. Developers often try to protect their products against malicious input by performing tests against inputs that are known to be bad, such as special characters that can invoke new commands. However, such lists often only account for the most well-known bad inputs. Attackers may be able to find other malicious inputs that were not expected by the developer, allowing them to bypass the intended protection mechanism.
CVE-2026-34177 has been classified to as a Denylist / Deny List vulnerability or weakness.
Products Associated with CVE-2026-34177
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Affected Versions
Canonical lxd:- Version 4.12.0 and below 5.0.7 is affected.
- Version 5.1.0 and below 5.21.5 is affected.
- Version 6.0.0 and below 6.8.0 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.