Bug 2452051 (CVE-2026-33898)

Summary: CVE-2026-33898 incus: Incus: Privilege escalation and unauthorized access due to improper authentication token validation in web UI
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Incus, a system container and virtual machine manager. The `incus webui` component incorrectly validates authentication tokens when they are passed in the URL. This vulnerability allows a local attacker, or a remote attacker who can trick a local user into interacting with the Incus UI web server, to gain unauthorized access. Successful exploitation could lead to privilege escalation or unauthorized access to Incus instances and potentially system resources.
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Bug Depends On: 2452105    
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Description OSIDB Bzimport 2026-03-27 00:01:47 UTC 
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.