CVE-2026-33897
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIncus 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIncus prior to 6.23.0 contains a critical vulnerability where pongo2 template engine, intended to be chroot-isolated to the instance filesystem, completely bypasses this isolation mechanism. This allows any user with template access to read or write arbitrary files on the host filesystem with root privileges.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 6.23.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Determine installed Incus versionRun 'incus version' or 'incusd --version' to retrieve the installed Incus version numberAffected if The version displayed is earlier than 6.23.0 (e.g., 6.22.0, 6.21.0, etc.)
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Identify configured instance templatesRun 'incus config template list <instance-name>' for each instance, or check for template files in /var/lib/incus/storage-pools/*/containers/*/templates/ or similar template directoriesAffected if One or more instance templates exist, particularly those using pongo2 syntax
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Check template file permissions and ownershipExamine template files for ownership by root and verify which Incus users or groups have read access to the templates directoryAffected if Templates are readable by non-root Incus users or the incus-user group, indicating template access is granted to authenticated users
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Verify if template processing is invokedReview Incus logs (journalctl -u incus or /var/log/incus/) for template-related operations such as 'incus config edit' triggering template generation, or check if instances use custom templates for cloud-init or similarAffected if Template processing has been executed on any instance, suggesting the vulnerable code path was reached
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Audit recent template-related operationsSearch Incus audit logs or system logs for file operations originating from template contexts that may indicate exploitation, such as unusual file reads/writes outside expected container pathsAffected if Template operations have accessed paths outside the expected container filesystem (e.g., /hostfs/ or absolute paths on the host)
The environment is affected if Incus version is earlier than 6.23.0 AND instance templates configured with pongo2 processing are accessible to authenticated users, allowing potential chroot bypass exploitation.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped6.23.0
Upgrade Incus to version 6.23.0 or later to patch the pongo2 chroot bypass. If immediate upgrade is not possible, restrict or disable instance templates until the patch can be applied.
6.23.0
- Check the current Incus version using 'incus version' or 'incus admin info'
- Consult the official Incus 6.23.0 release notes at github.com for specific upgrade instructions
- Use the appropriate package manager to upgrade Incus (e.g., 'apt update && apt install incus' for Debian/Ubuntu, or 'snap refresh incus' for snap installations)
- After upgrade, verify the new version is 6.23.0 or later using 'incus version'
- Test that container and VM operations still function correctly after the upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation2.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-33897 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-33897 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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