CVE-2026-33898 Local Incus UI web server vulnerable to nuthentication bypass

What is CVE-2026-33898?

CVE-2026-33898 is a high-severity authentication bypass vulnerability in lxc incus, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

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.

Weakness: CWE-287

Which versions are affected by CVE-2026-33898?

4 open source packages ship an affected version, including github.com/lxc/incus/v6/cmd/incus, github.com/lxc/incus and github.com/lxc/incus/v6. It affects 1 product.

Products include Linuxcontainers Incus.

How do I fix CVE-2026-33898?

Upgrade github.com/lxc/incus/v6/cmd/incus to 6.23.0 or later.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2026-33898 being exploited?

There is no known exploitation of CVE-2026-33898 in the wild and no public exploit code.

Other vulnerabilities in lxc incus

• CVE-2026-33897 Incus vulnerable to arbitrary file read and write through pongo templates Critical 10.0
• CVE-2026-33945 Abitrary file write through systemd-creds option Critical 10.0
• CVE-2026-23953 Incus container environment configuration newline injection High 8.7
• CVE-2026-23954 Incus container image templating arbitrary host file read and write High 8.7
• CVE-2025-64507 Incus vulnerable to local privilege escalation through custom storage volumes High 8.6

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2026-33898, GHSA-453r-g2pg-cxxq, GO-2026-4879, UBUNTU-CVE-2026-33898.