How severe is CVE-2026-33159?

No CVSS score has been assigned to CVE-2026-33159 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-33159?

CVE-2026-33159 affects the following packages: craftcms/cms (Packagist), craftcms/cms (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-33159?

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.

How do I detect CVE-2026-33159 in my Packagist dependencies?

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.

How do I mitigate CVE-2026-33159 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-33159 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-33159 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-33159?

CVE-2026-33159 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 24th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-33159?

CVE-2026-33159 is classified as Missing Authentication (CWE-306), CWE-862 (CWE-862). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-33159 published, and has it been updated?

CVE-2026-33159 was published on March 24, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2026-33159 — cms

Fix: craftcms/cms@7f0ead8

CVE-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

Also known asGHSA-6mrr-q3pj-h53w

Published

Mar 24, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 1, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk-0.12%

Lower risk than most CVEs24th percentile — riskier than 24% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

🐘craftcms/cms🐘craftcms/cms

Real-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

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

Guest POST to:

http POST /admin/actions/config-sync/index
Extract data from returned JS state:

Craft.updater = ... setState({"data":"<signedData>", ...});

Reuse data as a guest:

  POST /admin/actions/config-sync/regenerate-yaml
  data=<signedData>&<csrfParam>=<csrfToken>

  POST /admin/actions/config-sync/apply-yaml-changes
  data=<signedData>&<csrfParam>=<csrfToken>

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 pending YAML/config state, this can cause unauthorized config state transitions and a service integrity risk.

Resources

https://github.com/craftcms/cms/commit/7f0ead833f7

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`craftcms/cms`	≥ 5.0.0-RC1&&< 5.9.14	5.9.14`composer require craftcms/cms:^5.9.14`
🐘Packagist	`craftcms/cms`	≥ 4.0.0-RC1&&< 4.17.8	4.17.8`composer require craftcms/cms:^4.17.8`

Affected Products

1 product · 8 configurations

Application

craft cmscraftcms

> 5.0.0 && < 5.9.14

2 versions

4.0.05.0.0

Detection & mitigation playbook

Open-source dependency

Detect
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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### 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 `regenerateExternal

O3 Security · Impact-Aware SCA

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