CVE-2026-33158 — craftcms/cms
Fix: craftcms/cms@7290d91CVE-2026-33158 is a CWE-639 vulnerability in craftcms/cms. A fix is available for craftcms/cms — see the affected versions and patch details below.
Craft CMS: Low-privilege users could read private asset contents when editing an asset (IDOR)
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33158.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
craftcms/cms🐘craftcms/cmsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A low-privileged authenticated user can read private asset content by calling assets/edit-image with an arbitrary assetId that they are not authorized to view.
The endpoint returns image bytes (or a preview redirect) without enforcing a per-asset view authorization check, leading to potential unauthorized disclosure of private files.
Details
Root cause:
- A user-controlled object reference (
assetId) is used to load and return sensitive content. - The action does not verify whether the current user is authorized to view that asset.
- This creates an authenticated IDOR / authorization bypass.
Impact
- Craft installations where private/non-public assets exist and low-privileged users can authenticate.
Resources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | craftcms/cms | ≥ 4.0.0-RC1&&< 4.17.8 | 4.17.8composer require craftcms/cms:^4.17.8 |
| 🐘Packagist | craftcms/cms | ≥ 5.0.0-RC1&&< 5.9.14 | 5.9.14composer require craftcms/cms:^5.9.14 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for craftcms/cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update craftcms/cms to 4.17.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33158 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33158 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33158. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-33158 in your dependencies?
O3 Security finds CVE-2026-33158 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.