Vulnerability · Published Mar 26, 2026 · Assigned by GitHub_M
CVE-2026-33897Incus vulnerable to arbitrary file read and write through pongo templates
Critical 10.0
In plain English
A critical-severity security flaw in incus from lxc. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Incus is a system container and virtual machine manager. Prior to version 6.23.0, instance template files can be used to cause arbitrary read or writes as root on the host server. Incus allows for pongo2 templates within instances which can be used at various times in the instance lifecycle to template files inside of the instance. This particular implementation of pongo2 within Incus allowed for file read/write but with the expectation that the pongo2 chroot feature would isolate all such access to the instance's filesystem. This was allowed such that a template could theoretically read a file and then generate a new version of said file. Unfortunately the chroot isolation mechanism is entirely skipped by pongo2 leading to easy access to the entire system's filesystem with root privileges. Version 6.23.0 patches the issue.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | incus | 6.0.4-2+deb13u5 | DSA-6184-1 |
| Debian:13 | incus | 6.0.4-2+deb13u5 | DEBIAN-CVE-2026-33897 |
| Debian:14 | incus | 6.0.6-2 | DEBIAN-CVE-2026-33897 |
| Debian:12 | lxd | 5.0.2-5+deb12u4 | DSA-6188-1 |
| Debian:12 | lxd | no fix listed | DEBIAN-CVE-2026-33897 |
| Debian:13 | lxd | 5.0.2+git20231211.1364ae4-9+deb13u4 | DEBIAN-CVE-2026-33897 |
| Debian:13 | lxd | 5.0.2+git20231211.1364ae4-9+deb13u4 | DSA-6188-1 |
| Go | github.com/lxc/incus | no fix listed | GHSA-83xr-5xxr-mh92 |
| Go | github.com/lxc/incus | no fix listed | GO-2026-4881 |
| Go | github.com/lxc/incus/v6 | 6.23.0 | GHSA-83xr-5xxr-mh92 |
| Go | github.com/lxc/incus/v6 | 6.23.0 | GO-2026-4881 |
| Ubuntu:25.10 | incus | no fix listed | UBUNTU-CVE-2026-33897 |
| Ubuntu:26.10 | incus | no fix listed | UBUNTU-CVE-2026-33897 |
Affected products (as reported)
Weakness: CWE-1336 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
References
- https://github.com/lxc/incus/security/advisories/GHSA-83xr-5xxr-mh92 x_refsource_CONFIRM