CVE-2026-33159 — craftcms/cms
Fix: craftcms/cms@7f0ead8CVE-2026-33159 is a Missing Authentication vulnerability in craftcms/cms. A fix is available for craftcms/cms — see the affected versions and patch details below.
Craft CMS: Unauthenticated users could execute project configuration sync operations that should be restricted trusted users
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33159.
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
Craft CMS is a content management system (CMS). From version 4.0.0-RC1 to before version 4.17.8 and from version 5.0.0-RC1 to before version 5.9.14, guest users can access Config Sync updater index, obtain signed data, and execute state-changing Config Sync actions (regenerate-yaml, apply-yaml-changes) without authentication. This issue has been patched in versions 4.17.8 and 5.9.14.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | craftcms/cms | ≥ 5.0.0-RC1&&< 5.9.14 | 5.9.14composer require craftcms/cms:^5.9.14 |
| 🐘Packagist | craftcms/cms | ≥ 4.0.0-RC1&&< 4.17.8 | 4.17.8composer require craftcms/cms:^4.17.8 |
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 5.9.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33159 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-2026-33159 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33159. 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-2026-33159 in your dependencies?
O3 Security finds CVE-2026-33159 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.