Auth bypass in Craftcms Cms

CVE-2026-28781

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.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (33.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-28781: held from 0.003 to 0.004.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-28781?
CVE-2026-28781 is a medium-severity vulnerability in Craftcms Cms, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-03-04.
How severe is CVE-2026-28781?
Medium severity. CVSS v3 base score is 6.5 out of 10.