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Incus has an abitrary file write through its systemd-creds options

Critical severity GitHub Reviewed Published Mar 26, 2026 in lxc/incus • Updated Mar 27, 2026

Package

gomod github.com/lxc/incus/v6 (Go)

Affected versions

< 6.23.0

Patched versions

6.23.0

Description

Summary

Incus instances have an option to provide credentials to systemd in the guest. For containers, this is handled through a shared directory.
An attacker can use the name of a systemd credential to escape that directory and overwrite arbitrary files on the host system.

This can in turn be used to perform local privilege escalation or cause a DoS.

Details

An attacker can set a configuration key named something like systemd.credential.../../../../../../root/.bashrc to cause Incus to write outside of the credentials directory associated with the container. This makes use of the fact that the Incus syntax for such credentials is systemd.credential.XYZ where XYZ can itself contain more periods.

While it's not possible to read any data this way, it's possible to write to arbitrary files as root, enabling both privilege escalation and denial of service attacks.

Credit

This issue was discovered and reported by the team at 7asecurity

References

@stgraber stgraber published to lxc/incus Mar 26, 2026
Published by the National Vulnerability Database Mar 27, 2026
Published to the GitHub Advisory Database Mar 27, 2026
Reviewed Mar 27, 2026
Last updated Mar 27, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(21st percentile)

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

CVE-2026-33945

GHSA ID

GHSA-q4q8-7f2j-9h9f

Source code

Credits

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