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CVE-2026-28781

Craft Affected by Entries Authorship Spoofing via Mass Assignment

7.1 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
None

Exploit likelihood

0.39%Up 0.4 points since Mar 5, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.1

Craft Affected by Entries Authorship Spoofing via Mass Assignment

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.

Record
CVE-2026-28781
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-639, CWE-915
Updated
2026-11-02
EUVDEUVD-2026-9448 7.1

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.

Record
EUVD-2026-9448
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-2xfc-g69j-x2mp 5.7

Craft CMS: Entries Authorship Spoofing via Mass Assignment

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., 1 for the default Admin).

Steps to Reproduce

  1. Log in as the attacker
  2. Navigate to the "Entries" section and click "New Entry"
  3. Fill in the required fields
  4. Enable a proxy tool (e.g., Burp Suite) to intercept requests
  5. Click "Save" & Intercept the request
  6. In the request body, add a new parameter to the body params: &authorIds[]=<Victim_ID>
  7. Forward the request
  8. Log in as an admin / as with the victim account
  9. 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

Record
GHSA-2xfc-g69j-x2mp
CVSS 4.0
5.7 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P
Weakness
CWE-639, CWE-915
Updated
2026-11-02
NVD 7.1

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.

Record
CVE-2026-28781
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-639, CWE-915
Updated
2026-11-02
OSV 7.1

Craft Affected by Entries Authorship Spoofing via Mass Assignment

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.

Record
CVE-2026-28781
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-639, CWE-915
Updated
2026-11-02
OSVGHSA-2xfc-g69j-x2mp 5.7

Craft CMS: Entries Authorship Spoofing via Mass Assignment

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., 1 for the default Admin).

Steps to Reproduce

  1. Log in as the attacker
  2. Navigate to the "Entries" section and click "New Entry"
  3. Fill in the required fields
  4. Enable a proxy tool (e.g., Burp Suite) to intercept requests
  5. Click "Save" & Intercept the request
  6. In the request body, add a new parameter to the body params: &authorIds[]=<Victim_ID>
  7. Forward the request
  8. Log in as an admin / as with the victim account
  9. 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

Record
GHSA-2xfc-g69j-x2mp
CVSS 4.0
5.7 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P
Weakness
CWE-639, CWE-915
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
craftcms/cms
Packagist
 5.0.0-RC1 up to 5.9.0-beta.1
5.9.0-beta.1
craftcms/cms
Packagist
 4.0.0-RC1 up to 4.17.0-beta.1
4.17.0-beta.1
craftcms/cms
Packagist
 5.0.0-RC1 up to 5.9.0-beta.1, plus listed versions
5.0.05.0.15.0.25.0.35.0.4
Show 45 moreShow less
5.0.55.0.65.1.05.1.15.1.105.1.25.1.35.1.45.1.55.1.65.1.75.1.85.1.95.2.05.2.0-beta.15.2.0-beta.25.2.0-beta.35.2.0-beta.45.2.0-beta.55.2.0-beta.65.2.15.2.105.2.25.2.35.2.45.2.4.15.2.55.2.65.2.75.2.85.2.95.3.05.3.0-beta.15.3.0-beta.25.3.0.15.3.0.25.3.0.35.3.15.3.25.3.35.3.45.3.55.3.65.4.05.4.0.1
5.9.0-beta.1
craftcms/cms
Packagist
 4.0.0-RC1 up to 4.17.0-beta.1, plus listed versions
4.0.04.0.0-RC24.0.0-RC34.0.0.14.0.1
Show 45 moreShow less
4.0.24.0.34.0.44.0.54.0.5.14.0.5.24.0.64.1.04.1.0.14.1.0.24.1.14.1.24.1.34.1.44.1.4.14.10.04.10.0-beta.14.10.0-beta.24.10.14.10.24.10.34.10.44.10.54.10.64.10.74.10.84.11.04.11.0.14.11.0.24.11.14.11.24.11.34.11.44.11.54.12.04.12.14.12.24.12.34.12.44.12.4.14.12.54.12.64.12.6.14.12.74.12.8
4.17.0-beta.1

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-28781 is a high vulnerability (CVSS 7.1) in Craftcms Cms, published March 3, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.39%, the 33rd percentile. Fixed in craftcms/cms 5.9.0-beta.1.

References

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Left out here: 272 versions. The JSON record has them.

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