Incus vulnerable to arbitrary file read and write through pongo templates

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.9 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS

• CVE-2026-33897: 0.49% estimated exploitation activity in the next 30 days; percentile 42.15 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Instance template files can be used to cause arbitrary read or writes as root on the host server. Details 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. Credit This issue was discovered and reported by the team at 7asecurity

Published by the source

27 Mar 2026, 17:17 UTC

Last modified by the source

27 Mar 2026, 17:17 UTC

Source last checked

26 Oct 2026, 15:18 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-83xr-5xxr-mh92

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# Patch Next advisory brief: CVE-2026-33897

Advisory: Incus vulnerable to arbitrary file read and write through pongo templates
IDs: CVE-2026-33897, GHSA-83xr-5xxr-mh92
Record: https://patchnext.com/advisories/cve-2026-33897 (revision 1, source checked 26 Oct 2026, 15:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/lxc/incus/v6 6.23.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/lxc/incus/v6: affected < 6.23.0; fixed in 6.23.0
- Go github.com/lxc/incus: affected <= 0.7.0

## Suggested inspection (read-only)
- Go github.com/lxc/incus/v6: check the installed version with your package manager.
- Go github.com/lxc/incus: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/lxc/incus/v6, github.com/lxc/incus.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-83xr-5xxr-mh92 (GitHub-reviewed advisory GHSA-83xr-5xxr-mh92 lists affected ranges: Go github.com/lxc/incus/v6 >=0 =0 <=0.7.0)

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