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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

EPSS

• CVE-2026-42609: 0.46% estimated exploitation activity in the next 30 days; percentile 40.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

5 May 2026, 21:29 UTC

Last modified by the source

13 May 2026, 13:52 UTC

Source last checked

26 Oct 2026, 14:40 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rr73-568v-28f8

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# Patch Next advisory brief: CVE-2026-42609

Advisory: Grav Vulnerable to Administrative Account Disruption and Privilege De-escalation via User Overwrite Logic
IDs: CVE-2026-42609, GHSA-rr73-568v-28f8
Record: https://patchnext.com/advisories/cve-2026-42609 (revision 1, source checked 26 Oct 2026, 14:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getgrav/grav 2.0.0-beta.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getgrav/grav: affected < 2.0.0-beta.2; fixed in 2.0.0-beta.2

## Suggested inspection (read-only)
- Packagist getgrav/grav: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on getgrav/grav.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rr73-568v-28f8 (GitHub-reviewed advisory GHSA-rr73-568v-28f8 lists affected ranges: Packagist getgrav/grav >=0 <2.0.0-beta.2)

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