Craft CMS: Entries Authorship Spoofing via Mass AssignmentGHSA-2xfc-g69j-x2mp
Fix: craftcms/cms@830b403GHSA-2xfc-g69j-x2mp is a CWE-639 vulnerability in craftcms/cms. A fix is available for craftcms/cms — see the affected versions and patch details below.
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.
Exploitation and automatability from CISA’s SSVC triage for GHSA-2xfc-g69j-x2mp.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
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
Description
The entry creation process allows for Mass Assignment of the authorId attribute. A user with "Create Entries" permission can inject the authorIds[] (or authorId) parameter into the POST request, which the backend processes without verifying if the current user is authorized to assign authorship to others.
Normally, this field is not present in the request for users without the necessary permissions. By manually adding this parameter, an attacker can attribute the new entry to any user, including Admins. This effectively "spoofs" the authorship.
Proof of Concept
Prerequisites
- A user account with "Create Entries" permission for a section.
- Victim's account ID (e.g.,
1for the default Admin).
Steps to Reproduce
- Log in as the attacker
- Navigate to the "Entries" section and click "New Entry"
- Fill in the required fields
- Enable a proxy tool (e.g., Burp Suite) to intercept requests
- Click "Save" & Intercept the request
- In the request body, add a new parameter to the body params:
&authorIds[]=<Victim_ID> - Forward the request
- Log in as an admin / as with the victim account
- Go to entries & Observe the newly created entry is listed and the author is the victim account, not the actual creator
Impact
- A user can create entries that appear to belong to higher-privileged users, potentially bypassing review processes or gaining trust based on false authorship.
- An attacker could post malicious or inappropriate content attributed to an administrator or other trusted users.
Resources
https://github.com/craftcms/cms/commit/c6dcbdffaf6ab3ffe77d317336684d83699f4542 https://github.com/craftcms/cms/commit/830b403870cd784b47ae42a3f5a16e7ac2d7f5a8
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | craftcms/cms | ≥ 5.0.0-RC1&&< 5.9.0-beta.1 | 5.9.0-beta.1composer require craftcms/cms:^5.9.0-beta.1 |
| 🐘Packagist | craftcms/cms | ≥ 4.0.0-RC1&&< 4.17.0-beta.1 | 4.17.0-beta.1composer require craftcms/cms:^4.17.0-beta.1 |
Affected Products
craft cmscraftcmsDetection & 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 5.9.0-beta.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2xfc-g69j-x2mp 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.
Frequently Asked Questions
Is GHSA-2xfc-g69j-x2mp in your dependencies?
Find it across Packagist, including transitive dependencies.