---
id: CVE-2026-72915
title: 'Mastodon is a free, open-source social network server based on ActivityPub'
summary: >-
  Mastodon is a free, open-source social network server based on ActivityPub.
  From 4.6.0-beta.1 until 4.6.4 and 4.7.0-beta.1, any logged-in local user could
  use the show action in app/controllers/admin/collections_controller.rb to
  access p…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-200
published: '2026-08-10'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T20:55:04.493'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-72915'
references:
  - url: >-
      https://github.com/mastodon/mastodon/commit/467c933459c7d0e5513475b9e4888afaedfb1074
    label: security-advisories@github.com
  - url: >-
      https://github.com/mastodon/mastodon/commit/930aa9fee26bf9eaefe27826fa1061288d83373b
    label: security-advisories@github.com
  - url: 'https://github.com/mastodon/mastodon/releases/tag/v4.6.4'
    label: security-advisories@github.com
  - url: 'https://github.com/mastodon/mastodon/releases/tag/v4.7.0-beta.1'
    label: security-advisories@github.com
  - url: >-
      https://github.com/mastodon/mastodon/security/advisories/GHSA-hx34-2pfw-2qfj
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00483
epssPercentile: 0.39059
ingestedAt: '2026-09-09T21:22:45.526Z'
---

## Overview

Mastodon is a free, open-source social network server based on ActivityPub. From 4.6.0-beta.1 until 4.6.4 and 4.7.0-beta.1, any logged-in local user could use the show action in app/controllers/admin/collections_controller.rb to access personally identifying information about another local user in a collection because the controller used the general collection policy instead of the admin collection policy namespace. The exposed data included the other user's current email address and last-used IP address. This issue is fixed in versions 4.6.4 and 4.7.0-beta.1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.