GHSA-rr73-568v-28f8

Source

https://github.com/advisories/GHSA-rr73-568v-28f8

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-rr73-568v-28f8/GHSA-rr73-568v-28f8.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-rr73-568v-28f8

Aliases

CVE-2026-42609

Published

2026-05-05T21:29:53Z

Modified

2026-05-13T14:01:35.269807Z

Severity

8.1 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H CVSS Calculator

Summary

Grav Vulnerable to Administrative Account Disruption and Privilege De-escalation via User Overwrite Logic

Details

Summary

A business logic vulnerability in the Grav Admin Panel allows a low-privileged user (with only user creation permissions) to overwrite existing accounts, including the primary administrator. By creating a new user with a username that already exists, the system updates the existing account's metadata and permissions instead of rejecting the request. This leads to a Denial of Service (DoS) on administrative functions and Privilege De-escalation of the root account.

Details

The vulnerability stems from an insecure "Create or Update" logic within the user management module. When the admin-addon handles a user creation request, it does not strictly validate whether the username is already taken by a higher-privileged account. Instead of returning a "409 Conflict" or a validation error, the application logic proceeds to overwrite the existing user configuration file (e.g., user/accounts/root0.yaml) with the new, lower-privileged data provided by the attacker. Because the attacker cannot assign higher permissions to themselves (due to existing fixes), the result is that the targeted account (the original Admin/Root) has its access levels wiped or replaced by the attacker's input, effectively locking the real administrator out of the system.

PoC

Log in as a Super User (e.g., root0) and create a low-privileged user (e.g., adminuser).
Assign adminuser the following specific permissions: admin.login admin.users.list admin.users.read admin.users.create
Log out and log back in as adminuser.
Navigate to User Accounts -> Add.
Fill in the form with the following details: Username: root0 (The exact username of the Super User) Email: anything@grav.f Fullname: Fake Root0
Click Save.
Observe that the account is successfully "created".
The original administrative permissions are gone, and the account is now restricted.

PoC video

https://github.com/user-attachments/assets/047cb44e-0279-402b-b4fb-12bf5d427a5e

Impact

This is a Privilege De-escalation and Account Disruption vulnerability. Who is impacted: Any Grav installation where a non-admin user is granted permission to create other users. Consequence: An attacker can effectively disable all administrative accounts on the platform, leading to a complete loss of management control over the CMS.

Maintainer note — fix applied (2026-04-24)

Fixed in Grav core on the 2.0 branch: commit d904efc33 — will ship in 2.0.0-beta.2.

What changed: UserObject::save already had a uniqueness guard (commit 19c2f8da7, November 2025) that blocks the PoC. This release tightens that guard:

strpos($key, '@@') → str_contains($key, '@@'). The previous form was falsy when the transient-key marker was at position 0 (e.g. @@hash), silently bypassing the check. str_contains returns a proper boolean.
The instanceof FileStorage gate was dropped so the uniqueness check runs for any FlexStorageInterface backend — not just the default file-per-user YAML one.

A low-privileged user with admin.users.create can no longer disrupt a super-admin account by submitting that admin's username through the "add user" form.

Files: - system/src/Grav/Common/Flex/Types/Users/UserObject.php. - tests/unit/Grav/Common/Security/UserOverwriteSecurityTest.php — 3 tests pinning the PoC, the @@-prefix edge case, and pass-through for free usernames.

Database specific

{
    "nvd_published_at": "2026-05-11T16:17:33Z",
    "severity": "HIGH",
    "cwe_ids": [
        "CWE-269",
        "CWE-285",
        "CWE-639",
        "CWE-837"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-05T21:29:53Z"
}

References

Affected packages

Packagist / getgrav/grav

Package

Name: getgrav/grav
Purl: pkg:composer/getgrav/grav

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

2.0.0-beta.2

Affected versions

0.*

0.8.0

0.9.0

0.9.1

0.9.2

0.9.3

0.9.4

0.9.5

0.9.6

0.9.7

0.9.8

0.9.9

0.9.10

0.9.11

0.9.12

0.9.13

0.9.14

0.9.15

0.9.16

0.9.17

0.9.18

0.9.19

0.9.20

0.9.21

0.9.22

0.9.23

0.9.24

0.9.25

0.9.26

0.9.27

0.9.28

0.9.29

0.9.30

0.9.31

0.9.32

0.9.33

0.9.34

0.9.35

0.9.36

0.9.37

0.9.38

0.9.39

0.9.40

0.9.41

0.9.42

0.9.43

0.9.44

0.9.45

1.*

1.0.0-rc.1

1.0.0-rc.2

1.0.0-rc.3

1.0.0-rc.4

1.0.0-rc.5

1.0.0-rc.6

1.0.0

1.0.1

1.0.2

1.0.3

1.0.4

1.0.5

1.0.6

1.0.7

1.0.8

1.0.9

1.0.10

1.1.0-beta.1

1.1.0-beta.2

1.1.0-beta.3

1.1.0-beta.4

1.1.0-beta.5

1.1.0-rc.1

1.1.0-rc.2

1.1.0-rc.3

1.1.0

1.1.1

1.1.2

1.1.3

1.1.4

1.1.5

1.1.6

1.1.7

1.1.8

1.1.9-rc.1

1.1.9-rc.2

1.1.9-rc.3

1.1.9

1.1.10

1.1.11

1.1.12

1.1.13

1.1.14

1.1.15

1.1.16

1.1.17

1.2.0-rc.1

1.2.0-rc.2

1.2.0-rc.3

1.2.0

1.2.1

1.2.2

1.2.3

1.2.4

1.3.0-rc.1

1.3.0-rc.2

1.3.0-rc.3

1.3.0-rc.4

1.3.0-rc.5

1.3.0

1.3.1

1.3.2

1.3.3

1.3.4

1.3.5

1.3.6

1.3.7

1.3.8

1.3.9

1.3.10

1.4.0-beta.1

1.4.0-beta.2

1.4.0-beta.3

1.4.0-rc.1

1.4.0-rc.2

1.4.0

1.4.1

1.4.2

1.4.3

1.4.4

1.4.5

1.4.6

1.4.7

1.4.8

1.5.0-beta.1

1.5.0-beta.2

1.5.0-rc.1

1.5.0

1.5.1

1.5.2

1.5.3

1.5.4

1.5.5

1.5.6

1.5.7

1.5.8

1.5.9

1.5.10

1.6.0-beta.1

1.6.0-beta.2

1.6.0-beta.3

1.6.0-beta.4

1.6.0-beta.5

1.6.0-beta.6

1.6.0-beta.7

1.6.0-beta.8

1.6.0-rc.1

1.6.0-rc.2

1.6.0-rc.3

1.6.0-rc.4

1.6.0

1.6.1

1.6.2

1.6.3

1.6.4

1.6.5

1.6.6

1.6.7

1.6.8

1.6.9

1.6.10

1.6.11

1.6.12

1.6.13

1.6.14

1.6.15

1.6.16

1.6.17

1.6.18

1.6.19

1.6.20

1.6.21

1.6.22

1.6.23

1.6.24

1.6.25

1.6.26

1.6.27

1.6.28

1.6.29

1.6.30

1.6.31

1.7.0-beta.1

1.7.0-beta.2

1.7.0-beta.3

1.7.0-beta.4

1.7.0-beta.5

1.7.0-beta.6

1.7.0-beta.7

1.7.0-beta.8

1.7.0-beta.9

1.7.0-beta.10

1.7.0-rc.1

1.7.0-rc.2

1.7.0-rc.3

1.7.0-rc.4

1.7.0-rc.5

1.7.0-rc.6

1.7.0-rc.7

1.7.0-rc.8

1.7.0-rc.9

1.7.0-rc.10

1.7.0-rc.11

1.7.0-rc.12

1.7.0-rc.13

1.7.0-rc.14

1.7.0-rc.15

1.7.0-rc.16

1.7.0-rc.17

1.7.0-rc.18

1.7.0-rc.19

1.7.0-rc.20

1.7.0

1.7.1

1.7.3

1.7.4

1.7.5

1.7.6

1.7.7

1.7.8

1.7.9

1.7.10

1.7.12

1.7.13

1.7.14

1.7.15

1.7.16

1.7.17

1.7.18

1.7.19

1.7.20

1.7.21

1.7.22

1.7.23

1.7.24

1.7.25

1.7.26

1.7.26.1

1.7.27

1.7.27.1

1.7.28

1.7.29

1.7.29.1

1.7.30

1.7.31

1.7.32

1.7.33

1.7.34

1.7.35

1.7.36

1.7.37

1.7.37.1

1.7.38

1.7.39

1.7.39.1

1.7.39.2

1.7.39.3

1.7.39.4

1.7.40

1.7.41

1.7.41.1

1.7.41.2

1.7.42

1.7.42.1

1.7.42.2

1.7.42.3

1.7.43

1.7.44

1.7.45

1.7.46

1.7.47

1.7.48

1.7.49

1.7.49.1

1.7.49.2

1.7.49.3

1.7.49.4

1.7.49.5

1.7.51

1.7.52

1.8.0-beta.1

1.8.0-beta.2

1.8.0-beta.3

1.8.0-beta.4

1.8.0-beta.5

1.8.0-beta.6

1.8.0-beta.7

1.8.0-beta.8

1.8.0-beta.9

1.8.0-beta.10

1.8.0-beta.11

1.8.0-beta.12

1.8.0-beta.13

1.8.0-beta.14

1.8.0-beta.15

1.8.0-beta.16

1.8.0-beta.17

1.8.0-beta.18

1.8.0-beta.19

1.8.0-beta.20

1.8.0-beta.21

1.8.0-beta.22

1.8.0-beta.23

1.8.0-beta.24

1.8.0-beta.25

1.8.0-beta.26

1.8.0-beta.27

1.8.0-beta.28

1.8.0-beta.29

2.*

2.0.0-beta.1

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-rr73-568v-28f8/GHSA-rr73-568v-28f8.json"