Craft CMS: Unauthenticated Users Can Perform Restricted Project Config Sync Operations

Exploitation

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

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-33159: 0.38% estimated exploitation activity in the next 30 days; percentile 31.59 (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 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. Details ConfigSyncController extends BaseUpdaterController, and the base updater is anonymously accessible for control panel requests. index emits signed updater state (data), which can be reused by guests in subsequent requests. Sensitive actions that are reachable via this method are actionApplyYamlChanges, actionRegenerateYaml, applyExternalChanges, and regenerateExternalConfig. Reproduction steps 1. Guest POST to: http POST /admin/actions/config-sync/index 2. Extract data from returned JS state: Craft.updater = ... setState({"data":"<signedData", ...}); 3. Reuse data as a guest: or 4. Observe completed response and state/file changes. Impact Unauthenticated users can execute project configuration sync operations that should be restricted to trusted admin/deployment contexts. Depending on the…

Published by the source

24 Mar 2026, 16:57 UTC

Last modified by the source

25 Mar 2026, 20:59 UTC

Source last checked

26 Oct 2026, 14:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-6mrr-q3pj-h53w

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# Patch Next advisory brief: CVE-2026-33159

Advisory: Craft CMS: Unauthenticated Users Can Perform Restricted Project Config Sync Operations
IDs: CVE-2026-33159, GHSA-6mrr-q3pj-h53w
Record: https://patchnext.com/advisories/cve-2026-33159 (revision 1, source checked 26 Oct 2026, 14:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: craftcms/cms 5.9.14, 4.17.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist craftcms/cms: affected >= 5.0.0-RC1, <= 5.9.13; >= 4.0.0-RC1, <= 4.17.7; fixed in 5.9.14, 4.17.8

## Suggested inspection (read-only)
- Packagist craftcms/cms: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on craftcms/cms.
- 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-6mrr-q3pj-h53w (GitHub-reviewed advisory GHSA-6mrr-q3pj-h53w lists affected ranges: Packagist craftcms/cms >=5.0.0-RC1 =4.0.0-RC1 <=4.17.7)

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