incus: Improper Access Control
CVE-2026-55621 is a high-severity improper access control vulnerability in incus from Lxc, with a CVSS 3.1 base score of 7.7 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected incus versions: < 7.2.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.41% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of incus you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Lxc | incus | < 7.2.0 | Not stated |
| Canonical | lxd | >= 4.12.0, < 5.0.7; >= 5.1.0, 5.21.5; >= 6.0.0, < 6.8.0 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N. Scored by CNA (github.com).
Official description
Incus is a system container and virtual machine manager. Prior to version 7.2.0, missing authorization checks exist for custom volume copying where an attacker knowing the name of a project that they don't have access to and the name of a custom volume in that project can copy the custom volume to a new project. This issue could allow an attacker to access secrets in custom volumes they are not authorized to access. Version 7.2.0 patches the issue.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
How developers prevent this class of flaw
- Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Other vulnerabilities in incus
- 9.9 Critical severity
- 7.7 High severity
- 9.9 Critical severity
- 7.1 High severity
- 8.5 High severity
- 7.1 High severity
Recent Improper Access Control vulnerabilities
- 7.7 High severity
- 9.1 Critical severity
- 7.2 High severity
- 8.8 High severity
- 9.4 Critical severity
- 9.4 Critical severity
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