Description
Mastodon is a free, open-source social network server based on ActivityPub. In versions there is a missing condition in the check if remote accounts consented to be featured in a remote Collection could lead to attackers bypassing the check and faking consent. An attacker could forge the FeatureAuthorization object that is used to verify consent to be featured in a Collection and thus make it appear as if an account is allowed to be in a Collection when it actually is not. While the FeatureAuthorization must reside on the same domain as the object it is for, a check is missing to make sure said object is actually the same as in the Collection item. This allows an attacker to forge the authorization. Mastodon servers are affected only if running the main branch or nightly builds who have opted into testing the experimental "Collections" feature by setting the environment variable EXPERIMENTAL_FEATURES to a value including collections. This has been patched in version 4.6.0-beta.1.
Published: 2026-06-15
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

No analysis available yet.

Remediation

No remediation available yet.

Tracking

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Advisories

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History

Tue, 16 Jun 2026 14:00:00 +0000

Type Values Removed Values Added
First Time appeared Joinmastodon
Joinmastodon mastodon
Vendors & Products Joinmastodon
Joinmastodon mastodon

Mon, 15 Jun 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 15 Jun 2026 18:00:00 +0000

Type Values Removed Values Added
Description Mastodon is a free, open-source social network server based on ActivityPub. In versions there is a missing condition in the check if remote accounts consented to be featured in a remote Collection could lead to attackers bypassing the check and faking consent. An attacker could forge the FeatureAuthorization object that is used to verify consent to be featured in a Collection and thus make it appear as if an account is allowed to be in a Collection when it actually is not. While the FeatureAuthorization must reside on the same domain as the object it is for, a check is missing to make sure said object is actually the same as in the Collection item. This allows an attacker to forge the authorization. Mastodon servers are affected only if running the main branch or nightly builds who have opted into testing the experimental "Collections" feature by setting the environment variable EXPERIMENTAL_FEATURES to a value including collections. This has been patched in version 4.6.0-beta.1.
Title Mastodon has a consent-check bypass in its remote Collections
Weaknesses CWE-345
CWE-863
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'}


Subscriptions

Joinmastodon Mastodon
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-15T18:51:29.498Z

Reserved: 2026-05-19T22:36:16.883Z

Link: CVE-2026-47777

cve-icon Vulnrichment

Updated: 2026-06-15T18:51:25.902Z

cve-icon NVD

Status : Deferred

Published: 2026-06-15T18:16:35.287

Modified: 2026-06-16T15:51:29.037

Link: CVE-2026-47777

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-16T13:45:16Z

Weaknesses
  • CWE-345

    Insufficient Verification of Data Authenticity

  • CWE-863

    Incorrect Authorization