EUVD-2026-16490
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Lifecycle Timeline
4Description
Incus is a system container and virtual machine manager. Prior to version 6.23.0, the web server spawned by `incus webui` incorrectly validates the authentication token such that an invalid value will be accepted. `incus webui` runs a local web server on a random localhost port. For authentication, it provides the user with a URL containing an authentication token. When accessed with that token, Incus creates a cookie persisting that token without needing to include it in subsequent HTTP requests. While the Incus client correctly validates the value of the cookie, it does not correctly validate the token when passed int the URL. This allows for an attacker able to locate and talk to the temporary web server on localhost to have as much access to Incus as the user who ran `incus webui`. This can lead to privilege escalation by another local user or an access to the user's Incus instances and possibly system resources by a remote attack able to trick the local user into interacting with the Incus UI web server. Version 6.23.0 patches the issue.
Analysis
Authentication bypass in Incus webui (versions prior to 6.23.0) permits local or remote attackers to gain unauthorized access to the system container and virtual machine manager via an improperly validated authentication token. The vulnerability allows attackers who can reach the temporary localhost web server to escalate privileges to the level of the user running 'incus webui', enabling control over containers, virtual machines, and potentially underlying system resources. …
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Remediation
Within 24 hours: Audit all systems running Incus webui versions prior to 6.23.0 and verify no internet-facing exposure of the localhost webui service. Within 7 days: Implement network segmentation to restrict access to the Incus webui localhost port (default 8443) to trusted administrative networks only; disable webui if not operationally required. …
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External POC / Exploit Code
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